This document provides an introduction to a book about 12 brain rules gleaned from neuroscience research. It summarizes the goal of introducing readers to these rules and how they may apply to daily life, especially in school and work. Some examples of rules discussed are how exercise boosts brain power, people don't pay attention to boring things, the brain needs breaks and sleep to function well, and humans are natural explorers. The introduction emphasizes that the rules are not prescriptions but calls for further real-world research on applying neuroscience principles given gaps in understanding the human brain.

2. BRAIN RULES. Copyright © 2008 by John J. Medina.
All rights reserved. Printed in the United States of America.
No part of this book may be used or reproduced in any manner whatsoever
without written permission except in the case of brief quotations
embodied in critical articles or reviews.
Requests for permission should be addressed to:
Pear Press
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This book may be purchased for educational, business,
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www.pearpress.com.
First Pear Press trade paperback edition 2009
Edited by Tracy Cutchlow
Designed by Greg Pearson
Library of Congress Cataloging-In-Publication Data is available upon request.
ISBN-10: 0-9797777-4-7
ISBN-13: 978-0-9797777-4-5
10 9 8 7 6 5 4 3 2 1

3. To Joshua and Noah
Gratitude, my dear boys, for constantly reminding me
that age is not something that matters unless you are cheese.

5. contents
introduction 1
exercise 7
Rule #1: Exercise boosts brain power.
Our brains love motion ~ The incredible test-score booster ~ Will you age like
Jim or like Frank? ~ How oxygen builds roads for the brain
survival 29
Rule #2:The human brain evolved, too.
What’s uniquely human about us ~ A brilliant survival strategy ~ Meet your
brain ~ How we conquered the world
wiring 49
Rule #3: Every brain is wired differently.
Neurons slide, slither, and split ~ Experience makes the difference ~ Furious
brain development not once, but twice ~ The Jennifer Aniston neuron
attention 71
Rule #4:We don’t pay attention to boring things.
Emotion matters ~ Why there is no such thing as multitasking ~ We pay great
attention to threats, sex, and pattern matching ~ The brain needs a break!
short-term memory 95
Rule #5: Repeat to remember.
Memories are volatile ~ How details become splattered across the insides of our
brains ~ How the brain pieces them back together again ~ Where memories go
long-term memory 121
Rule #6: Remember to repeat.
If you don’t repeat this within 30 seconds, you’ll forget it ~ Spaced repetition
cycles are key to remembering ~ When floating in water could help your memory

6. sleep 149
Rule #7: Sleep well, think well.
The brain doesn’t sleep to rest ~ Two armies at war in your head ~ How to
improve your performance 34 percent in 26 minutes ~ Which bird are you? ~
Sleep on it!
stress 169
Rule #8: Stressed brains don’t learn the same way.
Stress is good, stress is bad ~ A villain and a hero in the toxic-stress battle ~ Why
the home matters to the workplace ~ Marriage intervention for happy couples
sensory integration 197
Rule #9: Stimulate more of the senses.
Lessons from a nightclub ~ How and why all of our senses work together ~
Multisensory learning means better remembering ~ What’s that smell?
vision 221
Rule #10: Vision trumps all other senses.
Playing tricks on wine tasters ~ You see what your brain wants to see, and it
likes to make stuff up ~ Throw out your PowerPoint
gender 241
Rule #11: Male and female brains are different.
Sexing humans ~ The difference between little girl best friends and little boy best
friends ~ Men favor gist when stressed; women favor details ~ A forgetting drug
exploration 261
Rule #12: We are powerful and natural explorers.
Babies are great scientists ~ Exploration is aggressive ~ Monkey see, monkey do
~ Curiosity is everything
acknowledgements 283
index 285

9. go ahead and multiply the number 8,388,628 x 2 in your head.
Can you do it in a few seconds? There is a young man who can double
that number 24 times in the space of a few seconds. He gets it right
every time. There is a boy who can tell you the precise time of day
at any moment, even in his sleep. There is a girl who can correctly
determine the exact dimensions of an object 20 feet away. There is
a child who at age 6 drew such lifelike and powerful pictures, she
got her own show at a gallery on Madison Avenue. Yet none of these
children could be taught to tie their shoes. Indeed, none of them
have an IQ greater than 50.
The brain is an amazing thing.
Your brain may not be nearly so odd, but it is no less
extraordinary. Easily the most sophisticated information-transfer
system on Earth, your brain is fully capable of taking the little black
squiggles on this piece of bleached wood and deriving meaning from
them. To accomplish this miracle, your brain sends jolts of electricity
crackling through hundreds of miles of wires composed of brain cells
introduction

10. BRAIN RULES
2
so small that thousands of them could fit into the period at the end
of this sentence. You accomplish all of this in less time than it takes
you to blink. Indeed, you have just done it. What’s equally incredible,
given our intimate association with it, is this: Most of us have no idea
how our brain works.
This has strange consequences. We try to talk on our cell phones
and drive at the same time, even though it is literally impossible for
our brains to multitask when it comes to paying attention. We have
created high-stress office environments, even though a stressed brain
is significantly less productive. Our schools are designed so that most
real learning has to occur at home. This would be funny if it weren’t
so harmful. Blame it on the fact that brain scientists rarely have a
conversation with teachers and business professionals, education
majors and accountants, superintendents and CEOs. Unless you have
the Journal of Neuroscience sitting on your coffee table, you’re out of
the loop.
This book is meant to get you into the loop.
12 brain rules
My goal is to introduce you to 12 things we know about how
the brain works. I call these Brain Rules. For each rule, I present
the science and then offer ideas for investigating how the rule
might apply to our daily lives, especially at work and school. The
brain is complex, and I am taking only slivers of information from
each subject—not comprehensive but, I hope, accessible. The Brain
Rules film, available at www.brainrules.net/dvd, is an integral part of
the project. You might use the DVD as an introduction, and then
jump between a chapter in the book and the illustrations online. A
sampling of the ideas you’ll encounter:
• For starters, we are not used to sitting at a desk for eight hours
a day. From an evolutionary perspective, our brains developed
while working out, walking as many as 12 miles a day. The brain
still craves that experience, especially in sedentary populations like

11. INTRODUCTION
3
our own. That’s why exercise boosts brain power (Brain Rule #1) in
such populations. Exercisers outperform couch potatoes in long-
term memory, reasoning, attention, and problem-solving tasks. I am
convinced that integrating exercise into our eight hours at work or
school would only be normal.
• As you no doubt have noticed if you’ve ever sat through a typical
PowerPoint presentation, people don’t pay attention to boring things
(Brain Rule #4). You’ve got seconds to grab someone’s attention and
only 10 minutes to keep it. At 9 minutes and 59 seconds, something
must be done to regain attention and restart the clock—something
emotional and relevant. Also, the brain needs a break. That’s why I
use stories in this book to make many of my points.
• Ever feel tired about 3 o’clock in the afternoon? That’s because
your brain really wants to take a nap. You might be more productive
if you did: In one study, a 26-minute nap improved NASA pilots’
performance by 34 percent. And whether you get enough rest at
night affects your mental agility the next day. Sleep well, think well
(Brain Rule #7).
• We’ll meet a man who can read two pages at the same time, one
with each eye, and remember everything in the pages forever. Most
of us do more forgetting than remembering, of course, and that’s why
we must repeat to remember (Brain Rule #5). When you understand
the brain’s rules for memory, you’ll see why I want to destroy the
notion of homework.
• We’ll find out why the terrible twos only look like active
rebellion but actually are a child’s powerful urge to explore. Babies
may not have a lot of knowledge about the world, but they know a
whole lot about how to get it. We are powerful and natural explorers
(Brain Rule #12), and this never leaves us, despite the artificial
environments we’ve built for ourselves.
no prescriptions
The ideas ending the chapters of this book are not a prescription.

12. BRAIN RULES
4
They are a call for real-world research. The reason springs from
what I do for a living. My research expertise is the molecular basis of
psychiatric disorders, but my real interest is in trying to understand
the fascinating distance between a gene and a behavior. I have been
a private consultant for most of my professional life, a hired gun for
research projects in need of a developmental molecular biologist with
such specialization. I have had the privilege of watching countless
research efforts involving chromosomes and mental function.
On such journeys, I occasionally would run across articles and
books that made startling claims based on “recent advances” in
brain science about how to change the way we teach people and do
business. And I would panic, wondering if the authors were reading
some literature totally off my radar screen. I speak several dialects
of brain science, and I knew nothing from those worlds capable of
dictating best practices for education and business. In truth, if we
ever fully understood how the human brain knew how to pick up a
glass of water, it would represent a major achievement.
There was no need to panic. You can responsibly train a skeptical
eye on any claim that brain research can without equivocation tell us
how to become better teachers, parents, business leaders, or students.
This book is a call for research simply because we don’t know enough
to be prescriptive. It is an attempt to vaccinate against mythologies
such as the “Mozart Effect,” left brain/right brain personalities, and
getting your babies into Harvard by making them listen to language
tapes while they are still in the womb.
back to the jungle
What we know about the brain comes from biologists who
study brain tissues, experimental psychologists who study behavior,
cognitive neuroscientists who study how the first relates to the
second, and evolutionary biologists. Though we know precious little
about how the brain works, our evolutionary history tells us this: The
brain appears to be designed to solve problems related to surviving

13. INTRODUCTION
5
in an unstable outdoor environment, and to do so in nearly constant
motion. I call this the brain’s performance envelope.
Each subject in this book—exercise, survival, wiring, attention,
memory, sleep, stress, sense, vision, gender, and exploration—
relates to this performance envelope. Motion translates to exercise.
Environmental instability led to the extremely flexible way our
brains are wired, allowing us to solve problems through exploration.
Learning from our mistakes so we could survive in the great outdoors
meant paying attention to certain things at the expense of others,
and it meant creating memories in a particular way. Though we have
been stuffing them into classrooms and cubicles for decades, our
brains actually were built to survive in jungles and grasslands. We
have not outgrown this.
I am a nice guy, but I am a grumpy scientist. For a study
to appear in this book, it has to pass what some at The Boeing
Company (for which I have done some consulting) call MGF: the
Medina Grump Factor. That means the supporting research for
each of my points must first be published in a peer-reviewed journal
and then successfully replicated. Many of the studies have been
replicated dozens of times. (To stay as reader-friendly as possible,
extensive references are not in this book but can be found at
www.brainrules.net.)
What do these studies show, viewed as a whole? Mostly this: If
you wanted to create an education environment that was directly
opposed to what the brain was good at doing, you probably would
design something like a classroom. If you wanted to create a business
environment that was directly opposed to what the brain was good
at doing, you probably would design something like a cubicle. And if
you wanted to change things, you might have to tear down both and
start over.
In many ways, starting over is what this book is all about.

15. exercise
Rule #1
Exercise boosts brain power.

17. if the cameras weren’t rolling and the media abuzz
with live reports, it is possible nobody would have
believed the following story:
A man had been handcuffed, shackled and thrown
into California’s Long Beach Harbor, where he was quickly fastened
to a floating cable. The cable had been attached at the other end to
70 boats, bobbing up and down in the harbor, each carrying a single
person. Battling strong winds and currents, the man then swam,
towing all 70 boats (and passengers) behind him, traveling 1.5 miles
to Queen’s Way Bridge. The man, Jack La Lanne, was celebrating his
birthday.
He had just turned 70 years old.
Jack La Lanne, born in 1914, has been called the godfather of
the American fitness movement. He starred in one of the longest-
running exercise programs produced for commercial television. A
prolific inventor, La Lanne designed the first leg-extension machines,
the first cable-fastened pulleys, and the first weight selectors, all now

18. BRAIN RULES
10
standard issue in the modern gym. He is even credited with inventing
an exercise that supposedly bears his name, the Jumping Jack. La
Lanne is now in his mid-90s, and even these feats are probably not
the most interesting aspect of this famed bodybuilder’s story.
If you ever have the chance to hear him in an interview, your
biggest impression will be not the strength of his muscles but the
strength of his mind. La Lanne is mentally alert, almost beyond
reason. His sense of humor is both lightening fast and improvisatory.
“I tell people I can’t afford to die. It will wreck my image!” he once
exclaimed to Larry King. He regularly rails at the camera: “Why am I
so strong? Do you know how many calories are in butter and cheese
and ice cream? Would you get your dog up in the morning for a cup of
coffee and a doughnut?” He claims he hasn’t had dessert since 1929.
He is hyper-energized, opinionated, possessed with the intellectual
vigor of an athlete in his 20s.
So it’s hard not to ask: “Is there a relationship between exercise
and mental alertness?” The answer, it turns out, is yes.
survival of the fittest
Though a great deal of our evolutionary history remains shrouded
in controversy, the one fact that every paleoanthropologist on the
planet accepts can be summarized in two words:
We moved.
A lot. When our bountiful rainforests began to shrink, collapsing
the local food supply, we were forced to wander around an
increasingly dry landscape looking for more trees we could scamper
up to dine. As the climate got more arid, these wet botanical vending
machines disappeared altogether. Instead of moving up and down
complex arboreal environments in three dimensions, which required
a lot of dexterity, we began walking back and forth across arid
savannahs in two dimensions, which required a lot of stamina.
“About 10 to 20 kilometers a day with men,” says famed
anthropologist Richard Wrangham, “and about half that for women.”

19. 1. EXERCISE
11
That’s the amount of ground scientists estimate we covered on a daily
basis back then—up to 12 miles a day. That means our fancy brains
developed not while we were lounging around but while we were
working out.
The first real marathon runner of our species was a vicious
predator known as Homo erectus. As soon as the Homo erectus family
evolved, about 2 million years ago, he started moving out of town.
Our direct ancestors, Homo sapiens, rapidly did the same thing,
starting in Africa 100,000 years ago and reaching Argentina by
12,000 years ago. Some researchers suggest that we were extending
our ranges by an unheard-of 25 miles per year.
This is an impressive feat, considering the nature of the world our
ancestors inhabited. They were crossing rivers and deserts, jungles
and mountain ranges, all without the aid of maps and mostly without
tools. They eventually made ocean-going boats without the benefit
of wheels or metallurgy, and then traveling up and down the Pacific
with only the crudest navigational skills. Our ancestors constantly
were encountering new food sources, new predators, new physical
dangers. Along the road they routinely suffered injuries, experienced
strange illnesses, and delivered and nurtured children, all without
the benefit of textbooks or modern medicine.
Given our relative wimpiness in the animal kingdom (we don’t
even have enough body hair to survive a mildly chilly night), what
these data tell us is that we grew up in top physical shape, or we
didn’t grow up at all. And they also tell us the human brain became
the most powerful in the world under conditions where motion was
a constant presence.
If our unique cognitive skills were forged in the furnace of
physical activity, is it possible that physical activity still influences
our cognitive skills? Are the cognitive abilities of someone in good
physical condition different from those of someone in poor physical
condition? And what if someone in poor physical condition were
whipped into shape? Those are scientifically testable questions. The

20. BRAIN RULES
12
answers are directly related to why Jack La Lanne can still crack jokes
about eating dessert. In his nineties.
will you age like jim or like frank?
We discovered the beneficial effects of exercise on the brain
by looking at aging populations. This was brought home to me by
an anonymous man named Jim and a famous man named Frank. I
met them both while I was watching television. A documentary on
American nursing homes showed people in wheelchairs, many in
their mid- to late 80s, lining the halls of a dimly lit facility, just sitting
around, seemingly waiting to die. One was named Jim. His eyes
seemed vacant, lonely, friendless. He could cry at the drop of a hat
but otherwise spent the last years of his life mostly staring off into
space. I switched channels. I stumbled upon a very young-looking
Mike Wallace. The journalist was busy interviewing architect Frank
Lloyd Wright, at the time in his late 80s. I was about to hear a most
riveting interview.
“When I walk into St. Patrick’s Cathedral … here in New York
City, I am enveloped in a feeling of reverence,” said Wallace, tapping
his cigarette. The old man eyed Wallace. “Sure it isn’t an inferiority
complex?”
“Just because the building is big and I’m small, you mean?”
“Yes.”
“I think not.”
“I hope not.”
“You feel nothing when you go into St. Patrick’s?”
“Regret,” Wright said without a moment’s pause, “because it isn’t
the thing that really represents the spirit of independence and the
sovereignty of the individual which I feel should be represented in
our edifices devoted to culture.”
I was dumbfounded by the dexterity of Wright’s response. In four
sentences, one could detect the clarity of his mind, his unshakable
vision, his willingness to think out of the box. The rest of his

21. 1. EXERCISE
13
interview was just as compelling, as was the rest of Wright’s life. He
completed the designs for the Guggenheim Museum, his last work,
in 1957, when he was 90 years old.
But I also was dumbfounded by something else. As I
contemplated Wright’s answers, I remembered Jim from the nursing
home. He was the same age as Wright. In fact, most of the residents
were. I suddenly was beholding two types of aging. Jim and Frank
lived in roughly the same period of time. But one mind had almost
completely withered, while the other remained as incandescent as
a light bulb. What was the difference in the aging process between
men like Jim and the famous architect? This question has bugged the
research community for a long time. Investigators have known for
years that some people age with energy and pizazz, living productive
lives well into their 80s and 90s. Others appear to become battered
and broken by the process, and often they don’t survive their
70s. Attempts to explain these differences led to many important
discoveries, which I have grouped as answers to six questions.
1) Is there one factor that predicts how well you will age?
It was never an easy question for researchers to answer. They
found many variables, from nature to nurture, that contributed
to someone’s ability to age gracefully. That’s why the scientific
community met with both applause and suspicion a group of
researchers who uncovered a powerful environmental influence. In
a result that probably produced a smile on Jack La Lanne’s face, one
of the greatest predictors of successful aging was the presence or
absence of a sedentary lifestyle. Put simply, if you are a couch potato,
you are more likely to age like Jim, if you make it to your 80s at all.
If you have an active lifestyle, you are more likely to age like Frank
Lloyd Wright and much more likely to make it to your 90s.
The chief reason for the difference seemed to be that exercise
improved cardiovascular fitness, which in turn reduced the risk for
diseases such as heart attacks and stroke. But researchers wondered

22. BRAIN RULES
14
why the people who were aging “successfully” also seemed to be
more mentally alert. This led to the obvious second question:
2) Were they?
Just about every mental test possible was tried. No matter how
it was measured, the answer was consistently yes: A lifetime of
exercise can result in a sometimes astonishing elevation in cognitive
performance, compared with those who are sedentary. Exercisers
outperform couch potatoes in tests that measure long-term
memory, reasoning, attention, problem-solving, even so-called fluid-
intelligence tasks. These tasks test the ability to reason quickly and
think abstractly, improvising off previously learned material in order
to solve a new problem. Essentially, exercise improves a whole host
of abilities prized in the classroom and at work.
Not every weapon in the cognitive arsenal is improved by
exercise. Short-term memory skills, for example, and certain types of
reaction times appear to be unrelated to physical activity. And, while
nearly everybody shows some improvement, the degree of benefit
varies quite a bit among individuals. Most important, these data,
strong as they were, showed only an association, not a cause. To show
the direct link, a more intrusive set of experiments had to be done.
Researchers had to ask:
3) Can you turn Jim into Frank?
The experiments were reminiscent of a makeover show.
Researchers found a group of couch potatoes, measured their brain
power, exercised them for a period of time, and re-examined their
brain power. They consistently found that when couch potatoes are
enrolled in an aerobic exercise program, all kinds of mental abilities
begin to come back online. Positive results were observed after as
little as four months of activity. It was the same story with school-
age children. In one recent study, children jogged for 30 minutes two
or three times a week. After 12 weeks, their cognitive performance

23. 1. EXERCISE
15
had improved significantly compared with pre-jogging levels. When
the exercise program was withdrawn, the scores plummeted back to
their pre-experiment levels. Scientists had found a direct link. Within
limits, it does appear that exercise can turn Jim into Frank, or at least
turn Jim into a sharper version of himself.
As the effects of exercise on cognition became increasingly
obvious, scientists began fine-tuning their questions. One of the
biggest—certainly one dearest to the couch-potato cohort—was:
What type of exercise must you do, and how much of it must be done
to get the benefit? I have both good news and bad news.
4) What’s the bad news?
Astonishingly, after years of investigation in aging populations,
the answer to the question of how much is not much. If all you do
is walk several times a week, your brain will benefit. Even couch
potatoes who fidget show increased benefit over those who do not
fidget. The body seems to be clamoring to get back to its hyperactive
Serengeti roots. Any nod toward this history, be it ever so small, is
met with a cognitive war whoop. In the laboratory, the gold standard
appears to be aerobic exercise, 30 minutes at a clip, two or three
times a week. Add a strengthening regimen and you get even more
cognitive benefit.
Of course, individual results vary, and no one should embark on a
rigorous program without consulting a physician. Too much exercise
and exhaustion can hurt cognition. The data merely point to the
fact that one should embark. Exercise, as millions of years traipsing
around the backwoods tell us, is good for the brain. Just how good
took everyone by surprise, as they answered the next question.
5) Can exercise treat brain disorders?
Given the robust effect of exercise on typical cognitive
performance, researchers wanted to know if it could be used to
treat atypical performance. What about diseases such as age-related

24. BRAIN RULES
16
dementia and its more thoroughly investigated cousin, Alzheimer’s
disease? What about affective disorders such as depression?
Researchers looked at both prevention and intervention. With
experiments reproduced all over the world, enrolling thousands of
people, often studied for decades, the results are clear. Your lifetime
risk for general dementia is literally cut in half if you participate in
leisure-time physical activity. Aerobic exercise seems to be the key.
With Alzheimer’s, the effect is even greater: Such exercise lowers
your odds of getting the disease by more than 60 percent.
How much exercise? Once again, a little goes a long way. The
researchers showed you have to participate in some form of exercise
just twice a week to get the benefit. Bump it up to a 20-minute walk
each day, and you can cut your risk of having a stroke—one of the
leading causes of mental disability in the elderly—by 57 percent.
The man most responsible for stimulating this line of inquiry
did not start his career wanting to be a scientist. He wanted to be an
athletics coach. His name is Dr. Steven Blair, and he looks uncannily
like Jason Alexander, the actor who portrayed George Costanza on
the old TV sitcom Seinfeld. Blair’s coach in high school, Gene Bissell,
once forfeited a football game after discovering that an official had
missed a call. Even though the league office balked, Bissell insisted
that his team be declared the loser, and the young Steven never
forgot the incident. Blair writes that this devotion to truth inspired
his undying admiration for rigorous, no-nonsense, statistical analysis
of the epidemiological work in which he eventually embarked. His
seminal paper on fitness and mortality stands as a landmark example
of how to do work with integrity in this field. The rigor of his findings
inspired other investigators. What about using exercise not only as
prevention, they asked, but as intervention, to treat mental disorders
such as depression and anxiety?
That turned out to be a good line of questioning. A growing body
of work now suggests that physical activity can powerfully affect the
course of both diseases. We think it’s because exercise regulates the

25. 1. EXERCISE
17
release of the three neurotransmitters most commonly associated
with the maintenance of mental health: serotonin, dopamine, and
norepinephrine. Although exercise cannot substitute for psychiatric
treatment, the role of exercise on mood is so pronounced that
many psychiatrists have begun adding a regimen of physical activity
to the normal course of therapy. But in one experiment with
depressed individuals, rigorous exercise was actually substituted for
antidepressant medication. Even when compared against medicated
controls, the treatment outcomes were astonishingly successful. For
both depression and anxiety, exercise is beneficial immediately and
over the long term. It is equally effective for men and women, and
the longer the program is deployed, the greater the effect becomes. It
is especially helpful for severe cases and for older people.
Most of the data we have been discussing concern elderly
populations. Which leads to the question:
6) Are the cognitive blessings of exercise only for the elderly?
As you ratchet down the age chart, the effects of exercise on
cognition become less clear. The biggest reason for this is that so
few studies have been done. Only recently has the grumpy scientific
eye begun to cast its gaze on younger populations. One of the best
efforts enrolled more than 10,000 British civil servants between the
ages of 35 and 55, examining exercise habits and grading them as
low, medium, or high. Those with low levels of physical activity were
more likely to have poor cognitive performance. Fluid intelligence,
the type that requires improvisatory problem-solving skills, was
particularly hurt by a sedentary lifestyle. Studies done in other
countries have confirmed the finding.
If only a small number of studies have been done in middle-age
populations, the number of studies saying anything about exercise
and children is downright microscopic. Though much more work
needs to be done, the data point in a familiar direction, though
perhaps for different reasons.

26. BRAIN RULES
18
To talk about some of these differences, I would like to introduce
you to Dr. Antronette Yancey. At 6 foot 2, Yancey is a towering,
beautiful presence, a former professional model, now a physician-
scientist with a deep love for children and a broad smile to buttress
the attitude. She is a killer basketball player, a published poet, and
one of the few professional scientists who also makes performance
art. With this constellation of talents, she is a natural to study the
effects of physical activity on developing minds. And she has
found what everybody else has found: Exercise improves children.
Physically fit children identify visual stimuli much faster than
sedentary ones. They appear to concentrate better. Brain-activation
studies show that children and adolescents who are fit allocate more
cognitive resources to a task and do so for longer periods of time.
“Kids pay better attention to their subjects when they’ve been
active,” Yancey says. “Kids are less likely to be disruptive in terms of
their classroom behavior when they’re active. Kids feel better about
themselves, have higher self-esteem, less depression, less anxiety. All
of those things can impair academic performance and attentiveness.”
Of course, there are many ingredients to the recipe of academic
performance. Finding out which components are the most
important—especially if you want improvement—is difficult enough.
Finding out whether exercise is one of those choice ingredients is
even tougher. But these preliminary findings show that we have
every reason to be optimistic about the long-term outcomes.
an exercise in road-building
Why exercise works so well in the brain, at a molecular level,
can be explained by competitive food eaters—or, less charitably,
professional pigs. There is an international association representing
people who time themselves on how much they can eat at a given
event. The association is called the International Federation of
Competitive Eating, and its crest proudly displays the slogan (I am
not making this up) In Voro Veritas—literally, “In Gorging, Truth.”

27. 1. EXERCISE
19
Like any sporting organization, competitive food eaters have their
heroes. The reigning gluttony god is Takeru “Tsunami” Kobayashi.
He is the recipient of many eating awards, including the vegetarian
dumpling competition (83 dumplings downed in 8 minutes),
the roasted pork bun competition (100 in 12 minutes), and the
hamburger competition (97 in 8 minutes). Kobayashi also is a world
champion hot-dog eater. One of his few losses was to a 1,089-pound
Kodiak bear. In a 2003 Fox televised special called Man vs. Beast, the
mighty Kobayashi consumed only 31 bunless dogs compared with
the ursine’s 50, all in about 2½ minutes. Kobayashi lost his hot-dog
crown in 2007 to Joey Chestnut, who ate 66 hot dogs in 12 minutes
(the Tsunami could manage only 63).
But my point isn’t about speed. It’s about what happens to all of
those hot dogs after they slide down the Tsunami’s throat. As with
any of us, his body uses its teeth and acid and wormy intestines to
tear the food apart and, if need be, reconfigure it.
This is done for more or less a single reason: to turn foodstuffs
into glucose, a type of sugar that is one of the body’s favorite energy
resources. Glucose and other metabolic products are absorbed into
the bloodstream via the small intestines. The nutrients travel to all
parts of the body, where they are deposited into cells, which make
up the body’s various tissues. The cells seize the sweet stuff like
sharks in a feeding frenzy. Cellular chemicals greedily tear apart
the molecular structure of glucose to extract its sugary energy. This
energy extraction is so violent that atoms are literally ripped asunder
in the process.
As in any manufacturing process, such fierce activity generates
a fair amount of toxic waste. In the case of food, this waste consists
of a nasty pile of excess electrons shredded from the atoms in the
glucose molecules. Left alone, these electrons slam into other
molecules within the cell, transforming them into some of the most
toxic substances known to humankind. They are called free radicals.
If not quickly corralled, they will wreck havoc on the innards of a cell

28. BRAIN RULES
20
and, cumulatively, on the rest of the body. These electrons are fully
capable, for example, of causing mutations in your very DNA.
The reason you don’t die of electron overdose is that the
atmosphere is full of breathable oxygen. The main function of oxygen
is to act like an efficient electron-absorbing sponge. At the same time
the blood is delivering foodstuffs to your tissues, it is also carrying
these oxygen sponges. Any excess electrons are absorbed by the
oxygen and, after a bit of molecular alchemy, are transformed into
equally hazardous—but now fully transportable—carbon dioxide. The
blood is carried back to your lungs, where the carbon dioxide leaves
the blood and you breathe it out. So, whether you are a competitive
eater or a typical one, the oxygen-rich air you inhale keeps the food
you eat from killing you.
Getting food into tissues and getting toxic electrons out obviously
are matters of access. That’s why blood has to be everywhere inside
you. Serving as both wait staff and haz-mat team, any tissue without
enough blood supply is going to starve to death—your brain included.
That’s important because the brain’s appetite for energy is enormous.
The brain represents only about 2 percent of most people’s body
weight, yet it accounts for about 20 percent of the body’s total energy
usage—about 10 times more than would be expected. When the
brain is fully working, it uses more energy per unit of tissue weight
than a fully exercising quadricep. In fact, the human brain cannot
simultaneously activate more than 2 percent of its neurons at any
one time. More than this, and the glucose supply becomes so quickly
exhausted that you will faint.
If it sounds to you like the brain needs a lot of glucose—and
generates a lot of toxic waste—you are right on the money. This
means the brain also needs lots of oxygen-soaked blood. How
much food and waste can the brain generate in just a few minutes?
Consider the following statistics. The three requirements for human
life are food, drink, and fresh air. But their effects on survival have
very different timelines. You can live for 30 days or so without food,

29. 1. EXERCISE
21
and you can go for a week or so without drinking water. Your brain,
however, is so active that it cannot go without oxygen for more than
5 minutes without risking serious and permanent damage. Toxic
electrons over-accumulate because the blood can’t deliver enough
oxygen sponges. Even in a healthy brain, the blood’s delivery system
can be improved. That’s where exercise comes in. It reminds me of a
seemingly mundane little insight that literally changed the history of
the world.
The man with the insight was named John Loudon McAdam.
McAdam, a Scottish engineer living in England in the early 1800s,
noticed the difficulty people had trying to move goods and supplies
over hole-filled, often muddy, frequently impassable dirt roads. He
got the splendid idea of raising the level of the road using layers of
rock and gravel. This immediately made the roads more stable, less
muddy, and less flood-prone. As county after county adopted his
process, now called macadamization, an astonishing after-effect
occurred. People instantly got more dependable access to one
another’s goods and services. Offshoots from the main roads sprang
up, and pretty soon entire countrysides had access to far-flung points
using stable arteries of transportation. Trade grew. People got richer.
By changing the way things moved, McAdam changed the way we
lived. What does this have to do with exercise? McAdam’s central
notion wasn’t to improve goods and services, but to improve access to
goods and services. You can do the same for your brain by increasing
the roads in your body, namely your blood vessels, through exercise.
Exercise does not provide the oxygen and the food. It provides your
body greater access to the oxygen and the food. How this works is
easy to understand.
When you exercise, you increase blood flow across the tissues
of your body. This is because exercise stimulates the blood vessels
to create a powerful, flow-regulating molecule called nitric oxide.
As the flow improves, the body makes new blood vessels, which
penetrate deeper and deeper into the tissues of the body. This allows

30. BRAIN RULES
22
more access to the bloodstream’s goods and services, which include
food distribution and waste disposal. The more you exercise, the
more tissues you can feed and the more toxic waste you can remove.
This happens all over the body. That’s why exercise improves the
performance of most human functions. You stabilize existing
transportation structures and add new ones, just like McAdam’s
roads. All of a sudden, you are becoming healthier.
The same happens in the human brain. Imaging studies have
shown that exercise literally increases blood volume in a region of the
brain called the dentate gyrus. That’s a big deal. The dentate gyrus
is a vital constituent of the hippocampus, a region deeply involved
in memory formation. This blood-flow increase, which may be the
result of new capillaries, allows more brain cells greater access to the
blood’s food and haz-mat teams.
Another brain-specific effect of exercise recently has become
clear, one that isn’t reminiscent of roads so much as of fertilizer.
At the molecular level, early studies indicate that exercise also
stimulates one of the brain’s most powerful growth factors, BDNF.
That stands for Brain Derived Neurotrophic Factor, and it aids in the
development of healthy tissue. BDNF exerts a fertilizer-like growth
effect on certain neurons in the brain. The protein keeps existing
neurons young and healthy, rendering them much more willing
to connect with one another. It also encourages neurogenesis, the
formation of new cells in the brain. The cells most sensitive to this
are in the hippocampus, inside the very regions deeply involved in
human cognition. Exercise increases the level of usable BDNF inside
those cells. The more you exercise, the more fertilizer you create—at
least, if you are a laboratory animal. There are now suggestions that
the same mechanism also occurs in humans.
we can make a comeback
All of the evidence points in one direction: Physical activity
is cognitive candy. We can make a species-wide athletic comeback.

31. 1. EXERCISE
23
All we have to do is move. When people think of great comebacks,
athletes such as Lance Armstrong or Paul Hamm usually come to
mind. One of the greatest comebacks of all time, however, occurred
before both of these athletes were born. It happened in 1949 to the
legendary golfer Ben Hogan.
Prickly to the point of being obnoxious (he once quipped of
a competitor, “If we could have just screwed another head on his
shoulders, he would have been the greatest golfer who ever lived”),
Hogan’s gruff demeanor underscored a fierce determination. He
won the PGA championship in 1946 and in 1948, the year in which
he was also named PGA Player of the Year. That all ended abruptly.
On a foggy night in the Texas winter of 1949, Hogan and his wife
were hit head-on by a bus. Hogan fractured every bone that could
matter to a golfer: collar bone, pelvis, ankle, rib. He was left with life-
threatening blood clots. The doctors said he might never walk again,
let alone play golf. Hogan ignored their prognostications. A year after
the accident, he climbed back onto the green and won the U.S. Open.
Three years later, he played one of the most successful single seasons
in professional golf. He won five of the six tournaments he entered,
including the first three major championships of the year (a feat
now known as the Hogan Slam). Reflecting on one of the greatest
comebacks in sports history, he said in his typically spicy manner,
“People have always been telling me what I can’t do.” He retired in
1971.
When I reflect on the effects of exercise on cognition and the
things we might try to recapture its benefits, I am reminded of such
comebacks. Civilization, while giving us such seemingly forward
advances as modern medicine and spatulas, also has had a nasty side
effect. It gave us more opportunities to sit on our butts. Whether
learning or working, we gradually quit exercising the way our
ancestors did. The result is like a traffic wreck.
Recall that our evolutionary ancestors were used to walking up to
12 miles per day. This means that our brains were supported for most

32. BRAIN RULES
24
of our evolutionary history by Olympic-caliber bodies. We were not
used to sitting in a classroom for 8 hours at a stretch. We were not
used to sitting in a cubicle for 8 hours at a stretch. If we sat around
the Serengeti for 8 hours—heck, for 8 minutes—we were usually
somebody’s lunch. We haven’t had millions of years to adapt to our
sedentary lifestyle. That means we need a comeback. Removing
ourselves from such inactivity is the first step. I am convinced that
integrating exercise into those 8 hours at work or school will not
make us smarter. It will only make us normal.
ideas
There is no question we are in an epidemic of fatness, a point I
will not belabor here. The benefits of exercise seem nearly endless
because its impact is systemwide, affecting most physiological
systems. Exercise makes your muscles and bones stronger, for
example, and improves your strength and balance. It helps regulate
your appetite, changes your blood lipid profile, reduces your risk for
more than a dozen types of cancer, improves the immune system,
and buffers against the toxic effects of stress (see Chapter 8). By
enriching your cardiovascular system, exercise decreases your risk
for heart disease, stroke, and diabetes. When combined with the
intellectual benefits exercise appears to offer, we have in our hands
as close to a magic bullet for improving human health as exists
in modern medicine. There must be ways to harness the effects of
exercise in the practical worlds of education and business.
Recess twice a day
Because of the increased reliance on test scores for school
survival, many districts across the nation are getting rid of physical
education and recess. Given the powerful cognitive effects of physical
activity, this makes no sense. Yancey, the model-turned-physican/
scientist/basketball player, describes a real-world test:
“They took time away from academic subjects for physical

33. 1. EXERCISE
25
education … and found that, across the board, [physical education]
did not hurt the kids’ performance on the academic tests. … [When]
trained teachers provided the physical education, the children
actually did better on language, reading and the basic battery of
tests.”
Cutting off physical exercise—the very activity most likely to
promote cognitive performance—to do better on a test score is like
trying to gain weight by starving yourself. What if a school district
inserted exercise into the normal curriculum on a regular basis, even
twice a day? After all of the children had been medically evaluated,
they’d spend 20 to 30 minutes each morning on formal aerobic
exercise; in the afternoon, 20 to 30 minutes on strengthening
exercises. Most populations studied see a benefit if this is done
only two or three times a week. If it worked, there would be many
ramifications. It might even reintroduce the notion of school
uniforms. Of what would the new apparel consist? Simply gym
clothes, worn all day long.
Treadmills in classrooms and cubicles
Remember the experiment showing that when children
aerobically exercised, their brains worked better, and when the
exercise was withdrawn, the cognitive gain soon plummeted? These
results suggested to the researchers that the level of fitness was not
as important as a steady increase in the oxygen supply to the brain
(otherwise the improved mental sharpness would not have fallen
off so rapidly). So they did another experiment. They found that
supplemental oxygen administered to young healthy adults without
exercise gave a similar cognitive improvement.
This suggests an interesting idea to try in a classroom (don’t
worry, it doesn’t involve oxygen doping to get a grade boost). What
if, during a lesson, the children were not sitting at desks but walking
on treadmills? Students might listen to a math lecture while walking
1 to 2 miles per hour, or study English on treadmills fashioned to

34. BRAIN RULES
26
accommodate a desktop. Treadmills in the classroom might harness
the valuable advantages of increasing the oxygen supply naturally and
at the same time harvest all the other advantages of regular exercise.
Would such a thing, deployed over a school year, change academic
performance? Until brain scientists and education scientists get
together to show real-world benefit, the answer is: Nobody knows.
The same idea could apply at work, with companies installing
treadmills and encouraging morning and afternoon breaks for
exercise. Board meetings might be conducted while people walked
2 miles per hour. Would that improve problem-solving? Would it
alter retention rates or change creativity the same way it does in the
laboratory?
The idea of integrating exercise into the workday may sound
foreign, but it’s not difficult. I put a treadmill in my own office, and
I now take regular breaks filled not with coffee but with exercise. I
even constructed a small structure upon which my laptop fits so I can
write email while I exercise. At first, it was difficult to adapt to such a
strange hybrid activity. It took a whopping 15 minutes to become fully
functional typing on my laptop while walking 1.8 miles per hour.
I’m not the only one thinking along these lines. Boeing, for
example, is starting to take exercise seriously in its leadership-
training programs. Problem-solving teams used to work late into the
night; now, all work has to be completed during the day so there’s
time for exercise and sleep. More teams are hitting all of their
performance targets. Boeing’s vice president of leadership has put a
treadmill in her office as well, and she reports that the exercise clears
her mind and helps her focus. Company leaders are now thinking
about how to integrate exercise into working hours.
There are two compelling business reasons for such radical ideas.
Business leaders already know that if employees exercised regularly, it
would reduce health-care costs. And there’s no question that cutting
in half someone’s lifetime risk of a debilitating stroke or Alzheimer’s
disease is a wonderfully humanitarian thing to do. But exercise

35. 1. EXERCISE
27
also could boost the collective brain power of an organization. Fit
employees are capable of mobilizing their God-given IQs better
than sedentary employees. For companies whose competitiveness
rests on creative intellectual horsepower, such mobilization could
mean a strategic advantage. In the laboratory, regular exercise
improves—sometimes dramatically so—problem-solving abilities,
fluid intelligence, even memory. Would it do so in business settings?
What types of exercise need to be done, and how often? That’s worth
investigating.

36. Summary
Rule #1
Exercise boosts brain power.
Our brains were built for walking—12 miles a day!
•
•
To improve your thinking skills,
•
• move.
Exercise gets blood to your brain, bringing it glucose
•
•
for energy and oxygen to soak up the toxic electrons
that are left over. It also stimulates the protein that keeps
neurons connecting.
Aerobic exercise just twice a week halves your risk of
•
•
general dementia. It cuts your risk of Alzheimer’s by 60
percent.
Get illustrations, audio, video, and more
at www.brainrules.net

37. survival
Rule #2
The human brain evolved, too.

39. When he was 4, my son Noah picked up a stick in our
backyard and showed it to me. “Nice stick you have
there, young fellow,” I said. He replied earnestly, “That’s
not a stick. That’s a sword! Stick ’em up!” And I raised my
hands to the air. We both laughed. The reason I remember this short
exchange is that as I went back into the house, I realized my son
had just displayed virtually every unique thinking ability a human
possesses—one that took several million years to manufacture. And
he did so in less than two seconds.
Heavy stuff for a 4-year-old. Other animals have powerful
cognitive abilities, too, and yet there is something qualitatively
different about the way humans think about things. The journey that
brought us from the trees to the savannah gave us some structural
elements shared by no other creature—and unique ways of using the
elements we do have in common. How and why did our brains evolve
this way?
Recall the performance envelope: The brain appears to be

40. BRAIN RULES
32
designed to (1) solve problems (2) related to surviving (3) in an
unstable outdoor environment, and (4) to do so in nearly constant
motion. The brain adapted this way simply as a survival strategy, to
help us live long enough to pass our genes on to the next generation.
That’s right: It all comes down to sex. Ecosystems are harsh, crushing
life as easily as supporting it. Scientists estimate 99.99% of all species
that have ever lived are extinct today. Our bodies, brains included,
latched on to any genetic adaptation that helped us survive. This not
only sets the stage for all of the Brain Rules, it explains how we came
to conquer the world.
There are two ways to beat the cruelty of the environment: You
can become stronger or you can become smarter. We chose the
latter. It seems most improbable that such a physically weak species
could take over the planet not by adding muscles to our skeletons
but by adding neurons to our brains. But we did, and scientists have
spent a great deal of effort trying to figure out how. Judy DeLoache
has studied this question extensively. She became a well-respected
researcher in an era when women were actively discouraged from
studying investigative science, and she is still going strong at the
University of Virginia. Her research focus, given her braininess?
Appropriately, it is human braininess itself. She is especially
interested in how human cognition can be distinguished from the
way other animals think about their respective worlds.
One of her major contributions was to identify the human
trait that really does separate us from the gorillas: the ability to
use symbolic reasoning. That’s what my son was doing when he
brandished his stick sword. When we see a five-sided geometric
shape, we’re not stuck perceiving it as a pentagon. We can just as
easily perceive the U.S. military headquarters. Or a Chrysler minivan.
Our brain can behold a symbolic object as real all by itself and yet,
simultaneously, also representing something else. Maybe somethings
else. DeLoache calls it Dual Representational Theory. Stated formally,
it describes our ability to attribute characteristics and meanings to

41. 2. SURVIVAL
33
things that don’t actually possess them. Stated informally, we can
make things up that aren’t there. We are human because we can
fantasize.
Draw a vertical line in your hand. Does it have to stay a vertical
line? Not if you know how to impute a characteristic onto something
it does not intrinsically possess. Go ahead and put a horizontal line
under it. Now you have the number 1. Put a dot on the top of it. Now
you have the letter “i.” The line doesn’t have to mean a line. The line
can mean anything you darn well think it should mean. The meaning
can become anchored to a symbol simply because it is not forced to
become anchored to anything else. The only thing you have to do is
get everybody to agree on what a symbol should mean.
We are so good at dual representation, we combine symbols to
derive layers of meaning. It gives us the capacity for language, and
for writing down that language. It gives us the capacity to reason
mathematically. It gives us the capacity for art. Combinations
of circles and squares become geometry and Cubist paintings.
Combinations of dots and squiggles become music and poetry. There
is an unbroken intellectual line between symbolic reasoning and
the ability to create culture. And no other creature is capable of doing
it.
This ability isn’t fully formed at birth. DeLoache was able to
show this in a powerful way. In DeLoache’s laboratory, a little girl
plays with a dollhouse. Next door is an identical room, but life-size.
DeLoache takes a small plastic dog and puts it under the dollhouse
couch, then encourages the child to go into the “big” living room
next door and find a “big” version of the dog. What does the little
girl do? If she is 36 months of age, DeLoache found, she immediately
goes to the big room, looks under the couch, and finds the big dog.
But if the child is 30 months old, she has no idea where to look. She
cannot reason symbolically and cannot connect the little room with
the big room. Exhaustive studies show that symbolic reasoning, this
all-important human trait, takes almost three years of experience to

42. BRAIN RULES
34
become fully operational. We don’t appear to do much to distinguish
ourselves from apes before we are out of the terrible twos.
a handy trait
Symbolic reasoning turned out to be a versatile gadget. Our
evolutionary ancestors didn’t have to keep falling into the same
quicksand pit if they could tell others about it; even better if they
learned to put up warning signs. With words and language, we could
extract a great deal of knowledge about our living situation without
always having to experience its harsh lessons directly. So it makes
sense that once our brains developed symbolic reasoning, we kept it.
The brain is a biological tissue; it follows the rules of biology. And
there’s no bigger rule in biology than evolution through natural
selection: Whoever gets the food survives; whoever survives gets to
have sex; and whoever has sex gets to pass his traits on to the next
generation. But what stages did we go through to reach that point?
How can we trace the rise of our plump, 3-pound intellects?
You might remember those old posters showing the development
of humankind as a series of linear and increasingly sophisticated
creatures. I have an old one in my office. The first drawing shows
a chimpanzee; the final drawing shows a 1970s businessman. In
between are strangely blended variations of creatures with names
like Peking man and Australopithecus. There are two problems with
this drawing. First, almost everything about it is wrong. Second,
nobody really knows how to fix the errors. One of the biggest reasons
for our lack of knowledge is that so little hard evidence exists. Most
of the fossilized bones that have been collected from our ancestors
could fit into your garage, with enough room left over for your
bicycle and lawn mower. DNA evidence has been helpful, and there
is strong evidence that we came from Africa somewhere between 7
million and 10 million years ago. Virtually everything else is disputed
by some cranky professional somewhere.
Understanding our intellectual progress has been just as difficult.

43. 2. SURVIVAL
35
Most of it has been charted by using the best available evidence:
tool-making. That’s not necessarily the most accurate way; even if
it were, the record is not very impressive. For the first few million
years, we mostly just grabbed rocks and smashed them into things.
Scientists, perhaps trying to salvage some of our dignity, called
these stones hand axes. A million years later, our progress still was
not very impressive. We still grabbed “hand axes,” but we began to
smash them into other rocks, making them more pointed. Now we
had sharper rocks.
It wasn’t much, but it was enough to begin untethering ourselves
from our East African womb, and indeed any other ecological niche.
Things got more impressive, from creating fire to cooking food.
Eventually, we migrated out of Africa in successive waves, our first
direct Homo sapien ancestors making the journey as little as 100,000
years ago. Then, 40,000 years ago, something almost unbelievable
happened. They appeared suddenly to have taken up painting and
sculpture, creating fine art and jewelry. No one knows why the
changes were so abrupt, but they were profound. Thirty-seven
thousand years later, we were making pyramids. Five thousand years
after that, rocket fuel.
What happened to start us on our journey? Could the growth
spurt be explained by the onset of dual-representation ability? The
answer is fraught with controversy, but the simplest explanation is
by far the clearest. It seems our great achievements mostly had to do
with a nasty change in the weather.
new rules for survival
Most of human prehistory occurred in climates like the jungles of
South America: steamy, humid, and in dire need of air conditioning.
It was comfortably predictable. Then the climate changed. Scientists
estimate that there have been no fewer than 17 Ice Ages in the past
40 million years. Only in a few places, such as the Amazonian and
African rainforests, does anything like our original, sultry, millions-

44. BRAIN RULES
36
of-years-old climate survive. Ice cores taken from Greenland
show that the climate staggers from being unbearably hot to being
sadistically cold. As little as 100,000 years ago, you could be born in
a nearly arctic environment but then, mere decades later, be taking
off your loincloth to catch the golden rays of the grassland sun.
Such instability was bound to have a powerful effect on any
creature forced to endure it. Most could not. The rules for survival
were changing, and a new class of creatures would start to fill the
vacuum created as more and more of their roommates died out.
That was the crisis our ancestors faced as the tropics of Northern
and Eastern Africa turned to dry, dusty plains—not immediately, but
inexorably—beginning maybe 10 million years ago. Some researchers
blame it on the Himalayas, which had reached such heights as to
disturb global atmospheric currents. Others blame the sudden
appearance of the Isthmus of Panama, which changed the mixing of
the Pacific and Atlantic ocean currents and disturbed global weather
patterns, as El Niños do today.
Whatever the reason, the changes were powerful enough to
disrupt the weather all over the world, including in our African
birthplace. But not too powerful, or too subtle—a phenomenon
called the Goldilocks Effect. If the changes had been too sudden,
the climatic violence would have killed our ancestors outright, and I
wouldn’t be writing this book for you today. If the changes had been
too slow, there may have been no reason to develop our talent for
symbolism and, once again, no book. Instead, like Goldilocks and the
third bowl of porridge, the conditions were just right. The change
was enough to shake us out of our comfortable trees, but it wasn’t
enough to kill us when we landed.
Landing was only the beginning of the hard work, however. We
quickly discovered that our new digs were already occupied. The
locals had co-opted the food sources, and most of them were stronger
and faster than we were. Faced with grasslands rather than trees,
we rudely were introduced to the idea of “flat.” It is disconcerting

45. 2. SURVIVAL
37
to think that we started our evolutionary journey on an unfamiliar
horizontal plane with the words “Eat me, I’m prey” taped to the back
of our evolutionary butts.
jazzin’ on a riff
You might suspect that the odds against our survival were great.
You would be right. The founding population of our direct ancestors
is not thought to have been much larger than 2,000 individuals;
some think the group was as small as a few hundred. How, then, did
we go from such a wobbly, fragile minority population to a staggering
tide of humanity 7 billion strong and growing? There is only one way,
according to Richard Potts, director of the Human Origins Program
at the Smithsonian’s National Museum of Natural History. You give
up on stability. You don’t try to beat back the changes. You begin
not to care about consistency within a given habitat, because such
consistency isn’t an option. You adapt to variation itself.
It was a brilliant strategy. Instead of learning how to survive in
just one or two ecological niches, we took on the entire globe. Those
unable to rapidly solve new problems or learn from mistakes didn’t
survive long enough to pass on their genes. The net effect of this
evolution was that we didn’t become stronger; we became smarter.
We learned to grow our fangs not in the mouth but in the head. This
turned out to be a pretty savvy strategy. We went on to conquer the
small rift valleys in Eastern Africa. Then we took over the world.
Potts calls his notion Variability Selection Theory, and it
attempts to explain why our ancestors became increasingly allergic
to inflexibility and stupidity. Little in the fossil record is clear about
the exact progression—another reason for bitter controversy—but
all researchers must contend with two issues. One is bipedalism; the
other has to do with our increasingly big heads.
Variability Selection Theory predicts some fairly simple things
about human learning. It predicts there will be interactions between
two powerful features of the brain: a database in which to store a

46. BRAIN RULES
38
fund of knowledge, and the ability to improvise off of that database.
One allows us to know when we’ve made mistakes. The other
allows us to learn from them. Both give us the ability to add new
information under rapidly changing conditions. Both may be relevant
to the way we design classrooms and cubicles.
Any learning environment that deals with only the database
instincts or only the improvisatory instincts ignores one half of our
ability. It is doomed to fail. It makes me think of jazz guitarists:
They’re not going to make it if they know a lot about music theory
but don’t know how to jam in a live concert. Some schools and
workplaces emphasize a stable, rote-learned database. They ignore
the improvisatory instincts drilled into us for millions of years.
Creativity suffers. Others emphasize creative usage of a database,
without installing a fund of knowledge in the first place. They ignore
our need to obtain a deep understanding of a subject, which includes
memorizing and storing a richly structured database. You get people
who are great improvisers but don’t have depth of knowledge. You
may know someone like this where you work. They may look like jazz
musicians and have the appearance of jamming, but in the end they
know nothing. They’re playing intellectual air guitar.
standing tall
Variability Selection Theory allows a context for dual
representation, but it hardly gets us to the ideas of Judy DeLoache
and our unique ability to invent calculus and write romance novels.
After all, many animals create a database of knowledge, and many
of them make tools, which they even use creatively. Still, it is not
as if chimpanzees write symphonies badly and we write them
well. Chimps can’t write them at all, and we can write ones that
make people spend their life savings on subscriptions to the New
York Philharmonic. There must have been something else in our
evolutionary history that made human thinking unique.
One of the random genetic mutations that gave us an adaptive

47. 2. SURVIVAL
39
advantage involved learning to walk upright. The trees were gone
or going, so we had to deal with something new in our experience:
walking increasingly long distances between food sources. That
eventually involved the specialized use of our two legs. Bipedalism
was an excellent solution to a vanishing rainforest. But it was also a
major change. At the very least, it meant refashioning the pelvis so
that it no longer propelled the back legs forward (which is what it
does for great apes). Instead, the pelvis had to be re-imagined as a
load-bearing device capable of keeping the head above the grass
(which is what it does for you). Walking on two legs had several
consequences. For one thing, it freed up our hands. For another, it
was energy-efficient. It used fewer calories than walking on four legs.
Our ancestral bodies used the energy surplus not to pump up our
muscles but to pump up our minds—to the point that our modern-
day brain, 2 percent of our body weight, sucks up 20 percent of the
energy we consume.
These changes in the structure of the brain led to the masterpiece
of evolution, the region that distinguishes humans from all other
creatures. It is a specialized area of the frontal lobe, just behind the
forehead, called the prefrontal cortex.
We got our first hints about its function from a man named
Phineas Gage, who suffered the most famous occupational injury
in the history of brain science. The injury didn’t kill him, but his
family probably wished it had. Gage was a popular foreman of a
railroad construction crew. He was funny, clever, hardworking, and
responsible, the kind of man any dad would be proud to call “son-in-
law.” On September 13, 1848, he set an explosives charge in the hole
of a rock using a tamping iron, a 3-foot rod about an inch in diameter.
The charge blew the rod into Gage’s head, entering just under the
eye and destroying most of his prefrontal cortex. Miraculously, Gage
survived, but he became tactless, impulsive, and profane. He left his
family and wandered aimlessly from job to job. His friends said he
was no longer Gage.

48. BRAIN RULES
40
This was the first real evidence that the prefrontal cortex
governs several uniquely human cognitive talents, called “executive
functions”: solving problems, maintaining attention, and inhibiting
emotional impulses. In short, this region controls many of the
behaviors that separate us from other animals. And from teenagers.
meet your brain
The prefrontal cortex is only the newest addition to the
brain. Three brains are tucked inside your head, and parts of their
structure took millions of years to design. (This “triune theory of the
brain” is one of several models scientists use to describe the brain’s
overarching structural organization.) Your most ancient neural
structure is the brain stem, or “lizard brain.” This rather insulting
label reflects the fact that the brain stem functions the same in you
as in a gila monster. The brain stem controls most of your body’s
housekeeping chores. Its neurons regulate breathing, heart rate,
sleeping, and waking. Lively as Las Vegas, they are always active,
keeping your brain purring along whether you’re napping or wide
awake.
Sitting atop your brain stem is what looks like a sculpture
of a scorpion carrying a slightly puckered egg on its back. The
Paleomammalian brain appears in you the same way it does in
many mammals, such as house cats, which is how it got its name.
It has more to do with your animal survival than with your human
potential. Most of its functions involve what some researchers
call the “four F’s”: fighting, feeding, fleeing, and … reproductive
behavior.
Several parts of this “second brain” play a large role in the Brain
Rules. The claw of the scorpion, called the amygdale, allows you
to feel rage. Or fear. Or pleasure. Or memories of past experiences
of rage, fear, or pleasure. The amygdala is responsible for both
the creation of emotions and the memories they generate. The
leg attaching the claw to the body of the scorpion is called the

49. 2. SURVIVAL
41
hippocampus. The hippocampus converts your short-term memories
into longer-term forms. The scorpion’s tail curls over the egg-
shaped structure like the letter “C,” as if protecting it. This egg is
the thalamus, one of the most active, well-connected parts of the
brain—a control tower for the senses. Sitting squarely in the center
of your brain, it processes signals sent from nearly every corner of
More illustrations at www.brainrules.net
you have three brains

50. BRAIN RULES
42
your sensory universe, then routes them to specific areas throughout
your brain.
How this happens is mysterious. Large neural highways run
overhead these two brains, combining with other roads, branching
suddenly into thousands of exits, bounding off into the darkness.
Neurons spark to life, then suddenly blink off, then fire again.
Complex circuits of electrical information crackle in coordinated,
repeated patterns, then run off into the darkness, communicating
their information to unknown destinations.
Arching above like a cathedral is your “human brain,” the cortex.
Latin for “bark,” the cortex is the surface of your brain. It is in deep
electrical communication with the interior. This “skin” ranges in
thickness from that of blotting paper to that of heavy-duty cardboard.
It appears to have been crammed into a space too small for its surface
area. Indeed, if your cortex were unfolded, it would be about the size
of a baby blanket.
It looks monotonous, slightly like the shell of a walnut, which
fooled anatomists for hundreds of years. Until World War I came
along, they had no idea each region of the cortex was highly
specialized, with sections for speech, for vision, for memory. World
War I was the first major conflict where large numbers of combatants
encountered shrapnel, and where medical know-how allowed them
to survive their injuries. Some of these injuries penetrated only to the
periphery of the brain, destroying tiny regions of cortex while leaving
everything else intact. Enough soldiers were hurt that scientists
could study in detail the injuries and the truly strange behaviors that
resulted. Horribly confirming their findings during World War II,
scientists eventually were able to make a complete structure-function
map of the brain—and see how it had changed over the eons.
They found that as our brains evolved, our heads did, too: They
were getting bigger all the time. Tilted hips and big heads are not
easy anatomical neighbors. The pelvis—and birth canal—can be
only so wide, which is bonkers if you are giving birth to children

51. 2. SURVIVAL
43
with larger and larger heads. A lot of mothers and babies died on the
way to reaching an anatomical compromise. Human pregnancies
are still remarkably risky without modern medical intervention.
The solution? Give birth while the baby’s head is small enough to
fit through the birth canal. The problem? You create childhood. The
brain could conveniently finish its developmental programs outside
the womb, but the trade-off was a creature vulnerable to predation
for years and not reproductively fit for more than a decade. That’s an
eternity if you make your living in the great outdoors, and outdoors
was our home address for eons. But it was worth it. During this time
of extreme vulnerability, you had a creature fully capable of learning
just about anything and, at least for the first few years, not good for
doing much else. This created the concept not only of learner but,
for adults, of teacher. It was in our best interests to teach well: Our
genetic survival depended upon our ability to protect the little ones.
Of course, it was no use having babies who took years to grow
if the adults were eaten before they could finish their thoughtful
parenting. Weaklings like us needed a tactic that could allow us to
outcompete the big boys in their home turf, leaving our new home
safer for sex and babies. We decided on a strange one. We decided to
try to get along with each other.
you scratch my back...
Suppose you are not the biggest person on the block, but you
have thousands of years to become one. What do you do? If you are
an animal, the most straightforward approach is becoming physically
bigger, like the alpha male in a dog pack, with selection favoring
muscle and bone. But there is another way to double your biomass.
It’s not by creating a body but by creating an ally. If you can establish
cooperative agreements with some of your neighbors, you can double
your power even if you do not personally double your strength. You
can dominate the world. Trying to fight off a woolly mammoth?
Alone, and the fight might look like Bambi vs. Godzilla. Two or three

52. BRAIN RULES
44
of you, however, coordinating your behaviors and establishing the
concept of “teamwork,” and you present a formidable challenge. You
can figure out how to compel the mammoth to tumble over a cliff,
for one. There is ample evidence that this is exactly what we did.
This changes the rules of the game. We learned to cooperate,
which means creating a shared goal that takes into account your
allies’ interests as well as your own. Of course, in order to understand
your allies’ interests, you must be able to understand others’
motivations, including their reward and punishment systems. You
need to know where their “itch” is.
Understanding how parenting and group behavior allowed us to
dominate our world may be as simple as understanding a few ideas
behind the following sentence: The husband died, and then the wife
died. There is nothing particularly interesting about that sentence,
but watch what happens when I add two small words at the end:
The husband died, and then the wife died of grief. All of a sudden we
have a view, however brief, into the psychological interior of the wife.
We have an impression of her mental state, perhaps even knowledge
about her relationship with her husband.
These inferences are the signature characteristic of something
called Theory of Mind. We activate it all the time. We try to see our
entire world in terms of motivations, ascribing motivations to our
pets and even to inanimate objects. (I once knew a guy who treated
his 25-foot sailboat like a second wife. Even bought her gifts!) The
skill is useful for selecting a mate, for navigating the day-to-day
issues surrounding living together, for parenting. Theory of Mind is
something humans have like no other creature. It is as close to mind
reading as we are likely to get.
This ability to peer inside somebody’s mental life and make
predictions takes a tremendous amount of intelligence and, not
surprisingly, brain activity. Knowing where to find fruit in the jungle
is cognitive child’s play compared with predicting and manipulating
other people within a group setting. Many researchers believe a direct

53. 2. SURVIVAL
45
line exists between the acquisition of this skill and our intellectual
dominance of the planet.
When we try to predict another person’s mental state, we have
physically very little to go on. Signs do not appear above a person’s
head, flashing in bold letters his or her motivations. We are forced
to detect characteristics that are not physically obvious at all. This
talent is so automatic, we hardly know when we do it. We began
doing it in every domain. Remember the line that we can transform
into a “1” and an “i”? Now you have dual representation: the line and
the thing the line represents. That means you have Judy DeLoache,
and that means you have us. Our intellectual prowess, from language
to mathematics to art, may have come from the powerful need to
predict our neighbor’s psychological interiors.
feeling it
It follows from these ideas that our ability to learn has deep
roots in relationships. If so, our learning performance may be deeply
affected by the emotional environment in which the learning takes
place. There is surprising empirical data to support this. The quality
of education may in part depend on the relationship between student
and teacher. Business success may in part depend on the relationship
between employee and boss.
I remember a story by a flight instructor I knew well. He told me
about the best student he ever had, and a powerful lesson he learned
about what it meant to teach her. The student excelled in ground
school. She aced the simulations, aced her courses. In the skies, she
showed surprisingly natural skill, quickly improvising even in rapidly
changing weather conditions. One day in the air, the instructor saw
her doing something naïve. He was having a bad day and he yelled
at her. He pushed her hands away from the airplane’s equivalent of a
steering wheel. He pointed angrily at an instrument. Dumbfounded,
the student tried to correct herself, but in the stress of the moment,
she made more errors, said she couldn’t think, and then buried her

54. BRAIN RULES
46
head in her hands and started to cry. The teacher took control of
the aircraft and landed it. For a long time, the student would not get
back into the same cockpit. The incident hurt not only the teacher’s
professional relationship with the student but the student’s ability to
learn. It also crushed the instructor. If he had been able to predict
how the student would react to his threatening behavior, he never
would have acted that way.
If someone does not feel safe with a teacher or boss, he or she
may not be able to perform as well. If a student feels misunderstood
because the teacher cannot connect with the way the student learns,
the student may become isolated. This lies at the heart of the flight
student’s failure. As we’ll see in the Stress chapter, certain types
of learning wither in the face of traumatic stress. As we’ll see in
the Attention chapter, if a teacher can’t hold a student’s interest,
knowledge will not be richly encoded in the brain’s database. As we
see in this chapter, relationships matter when attempting to teach
human beings. Here we are talking about the highly intellectual
venture of flying an aircraft. But its success is fully dependent upon
feelings.
It’s remarkable that all of this came from an unremarkable change
in the weather. But a clear understanding of this affords us our first
real insight into how humans acquire knowledge: We learned to
improvise off a database, with a growing ability to think symbolically
about our world. We needed both abilities to survive on the savannah.
We still do, even if we have exchanged it for classrooms and cubicles.

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Summary
Rule #2
The human brain evolved, too.
We don’t have one brain in our heads; we have three.
•
•
We started with a “lizard brain” to keep us breathing,
then added a brain like a cat’s, and then topped those with
the thin layer of Jell-O known as the cortex—the third,
and powerful,“human” brain.
We took over the Earth by adapting to change itself,
•
•
after we were forced from the trees to the savannah
when climate swings disrupted our food supply.
Going from four legs to two to walk on the savannah
•
•
freed up energy to develop a complex brain.
Symbolic reasoning is a uniquely human talent. It may
•
•
have arisen from our need to understand one another’s
intentions and motivations, allowing us to coordinate
within a group.
Get more at www.brainrules.net

57. wiring
Rule #3
Every brain is wired differently.

59. michael jordan’s athletic failures are puzzling, don’t
you think?
In 1994, one of the best basketball players in the
world—ESPN’s greatest athlete of the 20th
century—
decided to quit the game and take up baseball instead. Jordan failed
miserably, hitting .202 in his only full season, the lowest of any
regular player in the league that year. He simultaneously committed
11 errors in the outfield, also the league’s worst. Jordan’s performance
was so poor, he couldn’t even qualify for a triple-A farm team. Though
it seems preposterous that anyone with his physical ability would fail
at any athletic activity he put his mind to, the fact that Jordan did not
even make the minor leagues is palpable proof that you can.
His failure was that much more embarrassing because another
athletic legend, Ken Griffey Jr., was burning up the baseball diamond
that same year. Griffey was excelling at all of the skills Jordan seemed
to lack—and doing so in the majors, thank you. Griffey, then playing
for the red-hot Seattle Mariners, maintained this excellence for most

60. BRAIN RULES
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of the decade, batting .300 for seven years in the 1990s and at the
same time slugging out 422 home runs. He is, at this printing, sixth
on the all-time home-runs list.
Like Jordan, Griffey Jr. played in the outfield but, unlike Jordan,
he was known for catches so spectacular he seemed to float in the
air. Float in the air? Wasn’t that the space Jordan was accustomed to
inhabiting? But the sacred atmosphere of the baseball park refused to
budge for Jordan, and he eventually went back to what his brains and
muscles did better than anyone else’s, creating a legendary sequel to
a previously stunning basketball career.
What was going on in the bodies of these two athletes? What is
it about their brains’ ability to communicate with their muscles and
skeletons that made their talents so specialized? It has to do with
how their brains were wired. To understand what that means, we
will watch what happens in the brain as it is learning, discuss the
enormous role of experience in brain development—including how
identical twins having an identical experience will not emerge with
identical brains—and discover that we each have a Jennifer Aniston
neuron. I am not kidding.
fried eggs and blueberries
You have heard since grade school that living things are made
of cells, and for the most part, that’s true. There isn’t much that
complex biological creatures can do that doesn’t involve cells. You
may have little gratitude for this generous contribution to your
existence, but your cells make up for the indifference by ensuring
that you can’t control them. For the most part, they purr and hum
behind the scenes, content to supervise virtually everything you will
ever experience, much of which lies outside your awareness. Some
cells are so unassuming, they find their normal function only after
they can’t function. The surface of your skin, for example—all 9
pounds of it—literally is deceased. This allows the rest of your cells
to support your daily life free of wind, rain, and spilled nacho cheese

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at a basketball game. It is accurate to say that nearly every inch of
your outer physical presentation to the world is dead.
The biological structures of the cells that are alive are fairly easy
to understand. Most look just like fried eggs. The white of the egg
we call the cytoplasm; the center yolk is the nucleus. The nucleus
contains that master blueprint molecule and newly christened patron
saint of wrongfully convicted criminals: DNA. DNA possesses genes,
small snippets of biological instructions, that guide everything from
how tall you become to how you respond to stress. A lot of genetic
material fits inside that yolk-like nucleus. Nearly 6 feet of the stuff
are crammed into a space that is measured in microns. A micron is
1/25,000th
of an inch, which means putting DNA into your nucleus
is like taking 30 miles of fishing line and stuffing it into a blueberry.
The nucleus is a crowded place.
One of the most unexpected findings of recent years is that this
DNA, or deoxyribonucleic acid, is not randomly jammed into the
nucleus, as one might stuff cotton into a teddy bear. Rather, DNA is
folded into the nucleus in a complex and tightly regulated manner.
The reason for this molecular origami: cellular career options. Fold
the DNA one way and the cell will become a contributing member of
your liver. Fold it another way and the cell will become part of your
busy bloodstream. Fold it a third way and you get a nerve cell—and
the ability to read this sentence.
So what does one of those nerve cells look like? Take that fried
egg and smash it with your foot, splattering it across the floor. The
resulting mess may look like a many-pointed star. Now take one
tip of that star and stretch it out. Way out. Using your thumb, now
squish the farthest region of the point you just stretched. This creates
a smaller version of that multipronged shape. Two smashed stars
separated by a long, thin line. There’s your typical nerve. Nerve cells
come in many sizes and shapes, but most have this basic framework.
The foot-stomped fried-egg splatter is called the nerve’s cell body. The
many points on the resulting star are called dendrites. The region

62. BRAIN RULES
54
you stretched out is called an axon, and the smaller, thumb-induced
starburst at the farther end of the axon is called the axon terminal.
These cells help to mediate something as sophisticated as human
thought. To understand how, we must journey into the Lilliputian
world of the neuron, and to do that, I would like to borrow from
a movie I saw as a child. It was called Fantastic Voyage, written by
Harry Kleiner and popularized afterward in a book by legendary
science-fiction writer Isaac Asimov. Using a premise best described as
Honey, I Shrunk the Submarine, the film follows a group of researchers
exploring the internal workings of the human body—in a submersible
reduced to microscopic size. We are going to enter such a submarine,
which will allow us to roam around the insides of a typical nerve cell
and the watery world in which it is anchored. Our initial port of call
is to a neuron that resides in the hippocampus.
When we arrive at this hippocampal neuron, it looks as if
we’ve landed in an ancient, underwater forest. Somehow it has
become electrified, which means we are going to have to be careful.
Everywhere there are submerged jumbles of branches, limbs, and
large, trunk-like objects. And everywhere sparks of electric current
run up and down those trunks. Occasionally, large clouds of tiny
chemicals erupt from one end of the tree trunks, after the electricity
has convulsed through them.
These are not trees. These are neurons, with some odd structural
distinctions. Hovering close to one of them, for example, we realize
that the “bark” feels surprisingly like grease. That’s because it is
grease. In the balmy interior of the human body, the exterior of the
neuron, the phospholipid bilayer, is the consistency of Mazola oil.
It’s the interior structures that give a neuron its shape, much as the
human skeleton gives the body its shape. When we plunge into the
interior of the cell, one of the first things we will see is this skeleton.
So let’s plunge.
It’s instantly, insufferably overcrowded, even hostile, in here.
Everywhere we have to navigate through a dangerous scaffolding

63. 3. WIRING
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of spiky, coral-like protein formations: the neural skeleton. Though
these dense formations give the neuron its three-dimensional shape,
many of the skeletal parts are in constant motion—which means we
have to do a lot of dodging. Millions of molecules still slam against
our ship, however, and every few seconds we are jolted by electrical
discharges. We don’t want to stay long.
swimming laps
We escape from one end of the neuron. Instead of perilously
winding through sharp thickets of proteins, we now find ourselves
free-floating in a calm, seemingly bottomless watery canyon. In the
distance, we can see another neuron looming ahead.
We are in the space between the two neurons, called a synaptic
cleft, and the first thing we notice is that we are not alone. We
appear to be swimming with large schools of tiny molecules. They
are streaming out of the neuron we just visited and thrashing
helter-skelter toward the one we are facing. In a few seconds, they
reverse themselves, swimming back to the neuron we just left. It
instantly gobbles them up. These schools of molecules are called
neurotransmitters, and they come in a variety of molecular species.
They function like tiny couriers, and neurons use these molecules
to communicate information across the canyon (or, more properly,
the synaptic cleft). The cell that lets them escape is called the pre-
synaptic neuron, and the cell that receives them is called the post-
synaptic neuron.
Neurons release these chemicals into the synapse usually in
response to being electrically stimulated. The neuron that receives
them can react negatively or positively when it encounters these
chemicals. Working something like a cellular temper tantrum, the
neuron can turn itself off to the rest of the neuroelectric world (a
process termed inhibition). Or, the neuron can become electrically
stimulated. That allows a signal to be transferred from the pre-
synaptic neuron to the post: “I got stimulated and I am passing on

64. BRAIN RULES
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the good news to you.” Then the neurotransmitters return to the cell
of origin, a process appropriately termed re-uptake. When that cell
gobbles them up, the system is reset and ready for another signal.
As we look 360 degrees around our synaptic environment,
we notice that the neural forest, large and seemingly distant, is
surprisingly complicated. Take the two neurons between which we
are floating. We are between just two connection points. If you can
imagine two trees being uprooted by giant hands, turned 90 degrees
so the roots face each other, and then jammed together, you can
visualize the real world of two neurons interacting with each other
in the brain. And that’s just the simplest case. Usually, thousands of
neurons are jammed up against one another, all occupying a single
small parcel of neural real estate. The branches form connections
to one another in a nearly incomprehensible mass of branching
confusion. Ten thousand points of connection is typical, and each
connection is separated by a synapse, those watery canyons in which
we are now floating.
Gazing at this underwater hippocampal forest, we notice several
disturbing developments. Like snakes swaying to the rhythm of
some chemical flute, some of these branches appear to be moving.
Occasionally, the end of one neuron swells up, greatly increasing
in diameter. The terminal ends of other neurons split down the
middle like a forked tongue, creating two connections where there
was only one. Electricity crackles through these moving neurons
at a blinding 250 miles per hour, some quite near us, with clouds
of neurotransmitters filling the spaces between the trunks as the
electric current passes by.
What we should do now is take off our shoes and bow low in
the submarine, for we are on Holy Neural Ground. What we are
observing is the process of the human brain learning.
extreme makeover
Eric Kandel is the scientist mostly responsible for figuring out

65. 3. WIRING
57
the cellular basis of this process. For it, he shared the Nobel Prize
in 2000, and his most important discoveries would have made
inventor Alfred Nobel proud. Kandel showed that when people learn
something, the wiring in their brains changes. He demonstrated that
acquiring even simple pieces of information involves the physical
alteration of the structure of the neurons participating in the process.
Taken broadly, these physical changes result in the functional
organization and reorganization of the brain. This is astonishing. The
brain is constantly learning things, so the brain is constantly rewiring
itself.
Kandel first discovered this fact not by looking at humans but
by looking at sea slugs. He soon found, somewhat insultingly, that
human nerves learn things in the same way slug nerves learn things.
And so do lots of animals in between slugs and humans. The Nobel
Prize was awarded in part because his careful work described the
thought processes of virtually every creature with the means to
think.
We saw these physical changes while our submarine was
puttering around the synaptic space between two neurons. As
neurons learn, they swell, sway, and split. They break connections
in one spot, glide over to a nearby region, and form connections
with their new neighbors. Many stay put, simply strengthening their
electrical connections with each other, increasing the efficiency of
information transfer. You can get a headache just thinking about the
fact that deep inside your brain, at this very moment, bits of neurons
are moving around like reptiles, slithering to new spots, getting fat
at one end or creating split ends. All so that you can remember a few
things about Eric Kandel and his sea slugs.
But before Kandel, in the 18th
century, the Italian scientist
Vincenzo Malacarne did a surprisingly modern series of biological
experiments. He trained a group of birds to do complex tricks, killed
them all, and dissected their brains. He found that his trained birds
had more extensive folding patterns in specific regions of their

66. BRAIN RULES
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brains than his untrained birds. Fifty years later, Charles Darwin
noted similar differences between the brains of wild animals and
their domestic counterparts. The brains in wild animals were 15 to
30 percent larger than those of their tame, domestic counterparts.
It appeared that the cold, hard world forced the wild animals into a
constant learning mode. Those experiences wired their heads much
differently.
It is the same with humans. This can be observed in places
ranging from New Orleans’s Zydeco beer halls to the staid palaces
of the New York Philharmonic. Both are the natural habitat of
violin players, and violin players have really strange brains when
compared with non-violin players. The neural regions that control
their left hands, where complex, fine motor movement is required
on the strings, look as if they’ve been gorging on a high-fat diet.
These regions are enlarged, swollen and crisscrossed with complex
associations. By contrast, the areas controlling the right hand, which
draws the bow, looks positively anorexic, with much less complexity.
The brain acts like a muscle: The more activity you do, the
larger and more complex it can become. Whether that leads to more
intelligence is another issue, but one fact is indisputable: What you
do in life physically changes what your brain looks like. You can
wire and rewire yourself with the simple choice of which musical
instrument—or professional sport—you play.
some assembly required
How does this fantastic biology work? Infants provide a front-row
seat to one of the most remarkable construction projects on Earth.
Every newly born brain should come with a sticker saying “some
assembly required.” The human brain, only partially constructed
at birth, won’t be fully assembled for years to come. The biggest
construction programs aren’t finished until you are in your early 20s,
with fine-tuning well into your mid-40s.
When babies are born, their brains have about the same number

67. 3. WIRING
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of connections as adults have. That doesn’t last long. By the time
children are 3 years old, the connections in specific regions of their
brains have doubled or even tripled. (This has given rise to the
popular belief that infant brain development is the critical key to
intellectual success in life. That’s not true, but that’s another story.)
This doubling and tripling doesn’t last long, either. The brain soon
takes thousands of tiny pruning shears and trims back a lot of this
hard work. By the time children are 8 or so, they’re back to their
adult numbers. And if kids never went through puberty, that would
be the end of the story. In fact, it is only the middle of the story.
At puberty, the whole thing starts over again. Quite different
regions in the brain begin developing. Once again, you see frenetic
neural outgrowth and furious pruning back. It isn’t until parents
begin thinking about college financial aid for their high schoolers
that their brains begin to settle down to their adult forms (sort of).
It’s like a double-humped camel. From a connectivity point of view,
there is a great deal of activity in the terrible twos and then, during
the terrible teens, a great deal more.
Though that might seem like cellular soldiers obeying growth
commands in lockstep formation, nothing approaching military
precision is observed in the messy world of brain development. And
it is at this imprecise point that brain development meets Brain Rule.
Even a cursory inspection of the data reveals remarkable variation
in growth patterns from one person to the next. Whether examining
toddlers or teenagers, different regions in different children develop
at different rates. There is a remarkable degree of diversity in the
specific areas that grow and prune, and with what enthusiasm they
do so.
I’m reminded of this whenever I see the class pictures that
captured my wife’s journey through the American elementary-school
system. My wife went to school with virtually the same people for
her entire K–12 experience (and actually remained friends with most
of them). Though the teachers’ dated hairstyles are the subject of

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much laughter for us, I often focus on what the kids looked like back
then. I always shake my head in disbelief.
In the first picture, the kids are all in grade one. They’re about
the same age, but they don’t look it. Some kids are short. Some are
tall. Some look like mature little athletes. Some look as if they just
got out of diapers. The girls almost always appear older than the boys.
It’s even worse in the junior-high pictures of this same class. Some
of the boys look as if they haven’t developed much since third grade.
Others are clearly beginning to sprout whiskers. Some of the girls,
flat chested and uncurved, look a lot like boys. Some seem developed
enough to make babies.
Why do I bring this up? If we had X-ray eyes capable of
penetrating their little skulls, we would find that the brains of these
kids are just as unevenly developed as their bodies.
the jennifer aniston neuron
We are born into this world carrying a number of preset circuits.
These control basic housekeeping functions like breathing, heartbeat,
your ability to know where your foot is even if you can’t see it, and
so on. Researchers call this “experience independent” wiring. The
brain also leaves parts of its neural construction project unfinished
at birth, waiting for external experience to direct it. This “experience
expectant” wiring is related to areas such as visual acuity and perhaps
language acquisition. And, finally, we have “experience dependent”
wiring. It may best be explained with a story about Jennifer Aniston.
You might want to skip the next paragraph if you are squeamish.
Ready? A man is lying in surgery with his brain partially exposed
to the air. He is conscious. The reason he is not crying out in agony
is that the brain has no pain neurons. He can’t feel the needle-sharp
electrodes piercing his nerve cells. The man is about to have some
of his neural tissue removed—resected, in surgical parlance—
because of intractable, life-threatening epilepsy. Suddenly, one of the
surgeons whips out a photo of Jennifer Aniston and shows it to the

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patient. A neuron in the man’s head fires excitedly. The surgeon lets
out a war whoop.
Sound like a grade B movie? This experiment really happened.
The neuron in question responded to seven photographs of actress
Jennifer Aniston, while it practically ignored the 80 other images
of everything else, including famous and non-famous people. Lead
scientist Quian Quiroga said, “The first time we saw a neuron firing
to seven different pictures of Jennifer Aniston—and nothing else—
we literally jumped out of our chairs.” There is a neuron lurking in
your head that is stimulated only when Jennifer Aniston is in the
room.
A Jennifer Aniston neuron? How could this be? Surely there is
nothing in our evolutionary history suggesting that Jennifer Aniston
is a permanent denizen of our brain wiring. (Aniston wasn’t even
born until 1969, and there are regions in our brain whose designs are
millions of years old). To make matters worse, the researchers also
found a Halle Berry-specific neuron, a cell in the man’s brain that
wouldn’t respond to pictures of Aniston or anything else. Just Berry.
He also had a neuron specific to Bill Clinton. It no doubt was helpful
to have a sense of humor while doing this kind of brain research.
Welcome to the world of experience-dependent brain wiring,
where a great deal of the brain is hard-wired not to be hard-wired.
Like a beautiful, rigorously trained ballerina, we are hard-wired to be
flexible.
We can immediately divide the world’s brains into those who
know of Jennifer Aniston or Halle Berry and those who don’t. The
brains of those who do are not wired the same way as those who
don’t. This seemingly ridiculous observation underlies a much
larger concept. Our brains are so sensitive to external inputs that
their physical wiring depends upon the culture in which they find
themselves.
Even identical twins do not have identical brain wiring. Consider
this thought experiment: Suppose two adult male twins rent the

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Halle Berry movie Catwoman, and we in our nifty little submarine are
viewing their brains while they watch. Even though they are in the
same room, sitting on the same couch, the twins see the movie from
slightly different angles. We find that their brains are encoding visual
memories of the video differently, in part because it is impossible to
observe the video from the same spot. Seconds into the movie, they
are already wiring themselves differently.
One of the twins earlier in the day read a magazine story about
panned action movies, a picture of Berry figuring prominently on the
cover. While watching the video, this twin’s brain is simultaneously
accessing memories of the magazine. We observe that his brain is
busy comparing and contrasting comments from the text with the
movie and is assessing whether he agrees with them. The other twin
has not seen this magazine, so his brain isn’t doing this. Even though
the difference may seem subtle, the two brains are creating different
memories of the same movie.
That’s the power of the Brain Rule. Learning results in physical
changes in the brain, and these changes are unique to each
individual. Not even identical twins having identical experiences
possess brains that wire themselves exactly the same way. And you
can trace the whole thing to experience.
on the street where you live
Perhaps a question is now popping up in your brain: If every
brain is wired differently from every other brain, can we know
anything about the organ?
Well, yes. The brain has billions of cells whose collective electrical
efforts make a loving, wonderful you or, perhaps with less complexity,
Kandel’s sea slug. All of these nerves work in a similar fashion. Every
human comes equipped with a hippocampus, a pituitary gland, and
the most sophisticated thinking store of electrochemistry on the
planet: a cortex. These tissues function the same way in every brain.
How then can we explain the individuality? Consider a highway.

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The United States has one of the most extensive and complex ground
transportation systems in the world. There are lots of variations on
the idea of “road,” from interstate freeways, turnpikes, and state
highways to residential streets, one-lane alleys, and dirt roads.
Pathways in the human brain are similarly diverse. We have the
neural equivalents of large interstate freeways, turnpikes, and state
highways. These big trunks are the same from one person to the next,
functioning in yours about the same way they function in mine. So a
great deal of the structure and function of the brain is predictable, a
property that allows the word “science” to be attached to the end of
the word “neuro” and keeps people like me employed. Such similarity
may be the ultimate fruit of the double-humped developmental
program we talked of previously. That’s the experience-independent
wiring.
It’s when you get to the smaller routes—the brain’s equivalent of
residential streets, one-laners and dirt roads—that individual patterns
begin to show up. Every brain has a lot of these smaller paths, and in
no two people are they identical. The individuality is seen at the level
of the very small, but because we have so much of it, the very small
amounts to a big deal.
It is one thing to demonstrate that every brain is wired
differently from every other brain. It is another to say that this affects
intelligence. Two scientists, a behavioral theorist and a neurosurgeon,
offer differing perspectives on the subject. The theorist believes in
seven to nine categories of multiple intelligence. The neurosurgeon
also believes in multiple categories. He thinks there may be billions.
Meet Howard Gardner, psychologist, author, educator, and father
of the so-called Multiple Intelligences movement. Gardner had the
audacity to suggest that the competency of the human mind is too
multifaceted to be boiled down to simplistic numerical measures. He
threw out the idea of IQ tests, and then he attempted to reframe the
question of human intellectual skill. Like a cognitive Jane Goodall
in an urban jungle, Gardner and his colleagues observed real people

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in the act of learning—at school, at work, at play, at life. He began
to notice categories of intellectual talent that people used every day
that were not always identified as being “intelligent” and certainly
were not measurable by IQ tests. After thinking about things for a
long time, he published his findings in a book called Frames of Mind:
The Theory of Multiple Intelligences. It set off a firestorm of debate that
burns unabated to this day.
Gardner believes he has observed at least seven categories of
intelligence: verbal/linguistic, musical/rhythmic, logical/mathemati-
cal, spatial, bodily/kinesthetic, interpersonal, and intrapersonal. He
calls these “entry points” into the inner workings of the human mind.
The categories don’t always intersect with one another, and Gardner
has said, “If I know you’re very good in music, I can predict with just
about zero accuracy whether you’re going to be good or bad in other
things.”
Some researchers think Gardner is resting on his opinion, not on
his data. But none of his critics attack the underlying thesis that the
human intellect is multifaceted. To date, Gardner’s efforts represent
the first serious attempt to provide an alternative to numerical
descriptions of human cognition.
mapping the brain
But categories of intelligence may number more than 7 billion—
roughly the population of the world. You can get a sense of this
by watching skilled neurosurgeon George Ojemann examine the
exposed brain of a 4-year-old girl. Ojemann has a shock of white hair,
piercing eyes, and the quiet authority of someone who for decades
has watched people live and die in the operating room. He is one
of the great neurosurgeons of our time, and he is an expert at a
technique called electrical stimulation mapping.
He is hovering over a girl with severe epilepsy. She is fully
conscious, her brain exposed to the air. He is there to remove some
of her misbehaving brain cells. Before Ojemann takes out anything,

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however, he has to make a map. He wields a slender white wand
attached to a wire, a cortical stimulator, which sends out small,
unobtrusive electrical shocks to anything it touches. If it brushed
against your hand, you would feel only a slight tingly sensation.
Ojemann gently touches one end of the wand to an area of the
little girl’s brain and then asks her, “Did you feel anything?” She
says dreamily, “Somebody just touched my hand.” He puts a tiny
piece of paper on the area. He touches another spot. She exclaims,
“Somebody just touched my cheek!” Another tiny piece of paper.
This call and response goes on for hours. Like a neural cartographer,
Ojemann is mapping the various functions of his little patient’s brain,
with special attention paid to the areas close to her epileptic tissue.
These are tests of the little girl’s motor skills. For reasons not well
understood, however, epileptic tissues are often disturbingly adjacent
to critical language areas. So Ojemann also pays close attention
to the regions involved in language processing, where words and
sentences and grammatical concepts are stored. This child happens
to be bilingual, so language areas essential for both Spanish and
English will need to be mapped. A paper dot marked “S” is applied
to the regions where Spanish exists, and a small “E” where English is
stored. Ojemann does this painstaking work with every single patient
who undergoes this type of surgery. Why? The answer is a stunner.
He has to map each individual’s critical function areas because he
doesn’t know where they are.
Ojemann can’t predict the function of very precise areas in
advance of the surgery because no two brains are wired identically.
Not in terms of structure. Not in terms of function. For example,
from nouns to verbs to aspects of grammar, we each store language in
different areas, recruiting different regions for different components.
Bilingual people don’t even store their Spanish and their English in
similar places.
This individuality has fascinated Ojemann for years. He once
combined the brain maps for 117 patients he had operated on over

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the years. Only in one region did he find a spot where most people
had a critical language area, or CLA, and “most” means 79 percent of
the patients.
Data from electrical stimulation mapping give probably the most
dramatic illustration of the brain’s individuality. But Ojemann also
wanted to know how stable these differences were during life, and if
any of those differences predicted intellectual competence. He found
interesting answers to both questions. First, the maps are established
very early in life, and they remain stable throughout. Even if a decade
or two had passed between surgeries, the regions recruited for a
specific CLA remained recruited for that same CLA. Ojemann also
found that certain CLA patterns could predict language competency,
at least as measured by a pre-operative verbal IQ test. If you want to
be good at a language (or at least perform well on the test), don’t let
the superior temporal gyrus host your CLA. Your verbal performance
will statistically be quite poor. Also, make sure your overall CLA
pattern has a small and rather tightly focused footprint. If the pattern
is instead widely distributed, you will have a remarkably low score.
These findings are robust and age-independent. They have been
demonstrated in people as young as kindergartners and as old as Alan
Greenspan.
Not only are people’s brains individually wired, but those
neurological differences can, at least in the case of language, predict
performance.
ideas
Given these data, does it make any sense to have school systems
that expect every brain to learn like every other? Does it make
sense to treat everybody the same in business, especially in a global
economy replete with various cultural experiences? The data offer
powerful implications for how we should teach kids—and, when
they grow up and get a job, how we should treat them as employees. I
have a couple of concerns about our school system:

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1) The current system is founded on a series of expectations
that certain learning goals should be achieved by a certain age.
Yet there is no reason to suspect that the brain pays attention to
those expectations. Students of the same age show a great deal of
intellectual variability.
2) These differences can profoundly influence classroom perfor-
mance. This has been tested. For example, about 10 percent of stu-
dents do not have brains sufficiently wired to read at the age at which
we expect them to read. Lockstep models based simply on age are
guaranteed to create a counterproductive mismatch to brain biology.
What can we do about this?
Smaller class size
All else being equal, it has been known for many years that
smaller, more intimate schools create better learning environments
than megaplex houses of learning. The Brain Rule may help explain
why smaller is better.
Given that every brain is wired differently, being able to read a
student’s mind is a powerful tool in the hands of a teacher. As you
may recall from the Survival chapter, Theory of Mind is about as
close to mind reading as humans are likely to get. It is defined as
the ability to understand the interior motivations of someone else
and the ability to construct a predictable “theory of how their mind
works” based on that knowledge. This gives teachers critical access
to their students’ interior educational life. It may include knowledge
of when students are confused and when they are fully engaged. It
also gives sensitive teachers valuable feedback about whether their
teaching is being transformed into learning. It may even be the
definition of that sensitivity. I have come to believe that people with
advanced Theory of Mind skills possess the single most important
ingredient for becoming effective communicators of information.

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Students comprehend complex knowledge at different times
and at different depths. Because a teacher can keep track of only so
many minds, there must be a limit on the number of students in a
class—the smaller, the better. It is possible that small class sizes
predict better performance simply because the teacher can better
keep track of where everybody is. This suggests that an advanced skill
set in Theory of Mind predicts a good teacher. If so, existing Theory
of Mind tests could be used like Myers-Briggs personality tests to
reveal good teachers from bad, or to help people considering careers
as teachers.
Customized instruction
What of that old admonition to create more individualized
instruction within a grade level? It sits on some solid brain science.
Researcher Carol McDonald Connor is doing the first work I’ve seen
capable of handling these differences head-on. She and a colleague
combined a standard reading program with a bright and shiny new
computer program called A2i. The software uses artificial intelligence
to determine where the user’s reading competencies lie and then
adaptively tailor exercises for the student in order to fill in any gaps.
When used in conjunction with a standard reading class, the
software is wildly successful. The more students work with the
program, the better their scores become. Interestingly, the effect
is greatest when the software is used in conjunction with a normal
reading program. Teacher alone or software alone is not as effective.
As the instructor teaches the class in a normal fashion, students will,
given the uneven intellectual landscape, experience learning gaps.
Left untreated, these gaps cause students to fall further and further
behind, a normal and insidious effect of not being able to transform
instruction into apprehension. The software makes sure these gaps
don’t go untreated.
Is this the future? Attempting to individualize education is
hardly a new idea. Using code as a stand-in for human teaching is

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not revolutionary, either. But the combination might be a stunner. I
would like to see a three-pronged research effort between brain and
education scientists:
1) Evaluate teachers and teachers-to-be for advanced Theory of
Mind skills, using one of the four main tests that measure empathy.
Determine whether this affects student performance in a statistically
valid fashion.
2) Develop adaptive software for a variety of subjects and grade
levels. Test them for efficacy. Deploy the ones that work in a manner
similar to the experiment Connor published in the journal Science.
3) Test both ideas in various combinations. Add to the mix
environments where the student-teacher ratio is both typical and
optimized, and then compare the results.
The reason to do this is straightforward: You cannot change the
fact that the human brain is individually wired. Every student’s brain,
every employee’s brain, every customer’s brain is wired differently.
That’s the Brain Rule. You can either accede to it or ignore it. The
current system of education chooses the latter, to our detriment. It
needs to be torn down and newly envisioned, in a Manhattan Project-
size commitment to individualizing instruction. We might, among
other things, dismantle altogether grade structures based on age.
Companies could try Theory of Mind screening for leaders, along
with a method of “mass customization” that treats every employee
as an individual. I bet many would discover that they have a great
basketball player in their organization, and they’re asking him or her
to play baseball.

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Summary
Rule #3
Every brain is wired differently.
What you do and learn in life physically changes what
•
•
your brain looks like—it literally rewires it.
The various regions of the brain develop at different
•
•
rates in different people.
No two people’s brains store the same information in
•
•
the same way in the same place.
We have a great number of ways of being intelligent,
•
•
many of which don’t show up on IQ tests.
Get more at www.brainrules.net

79. attention
Rule #4
We don’t pay attention to boring things.

81. it was about 3 o’clock in the morning when I suddenly
was startled into consciousness by the presence of a
small spotlight sweeping across the walls of our living
room. In the moonlight, I could see the 6-foot frame of
a young man in a trenchcoat, clutching a flashlight and examining
the contents of our house. His other hand held something metallic,
glinting in the silvery light. As my sleepy brain was immediately and
violently aroused, it struck me that my home was about to be robbed
by someone younger than me, bigger than me, and in possession of a
firearm. Heart pounding, knees shaking, I crept to the phone, quickly
called the police, turned on the lights, went to stand guard outside
my children’s room, and prayed. Miraculously, a police car was
already in the vicinity and activated its sirens within a minute of my
phone call. This all happened so quickly that my would-be assailant
left his get-away car in our driveway, engine still running. He was
quickly apprehended.
That experience lasted only 45 seconds, but aspects of it are

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indelibly impressed in my memory, from the outline of the young
man’s coat to the shape of his firearm.
Does it matter to learning if we pay attention? The short answer
is: You bet it does. My brain fully aroused, I will never forget that
experience as long as I live. The more attention the brain pays
to a given stimulus, the more elaborately the information will be
encoded—and retained. That has implications for your employees,
your students, and your kids. A strong link between attention and
learning has been shown in classroom research both a hundred years
ago and as recently as last week. The story is consistent: Whether
you are an eager preschooler or a bored-out-of-your-mind undergrad,
better attention always equals better learning. It improves retention
of reading material, accuracy, and clarity in writing, math, science—
every academic category that has ever been tested.
So I ask this question in every college course I teach: “Given a
class of medium interest, not too boring and not too exciting, when
do you start glancing at the clock, wondering when the class will be
over?” There is always some nervous shuffling, a few smiles, then a
lot of silence. Eventually someone blurts out:
“Ten minutes, Dr. Medina.”
“Why 10 minutes?” I inquire.
“That’s when I start to lose attention. That’s when I begin to
wonder when this torment will be over.” The comments are always
said in frustration. A college lecture is still about 50 minutes long.
Peer-reviewed studies confirm my informal inquiry: Before the
first quarter-hour is over in a typical presentation, people usually
have checked out. If keeping someone’s interest in a lecture were
a business, it would have an 80 percent failure rate. What happens
at the 10-minute mark to cause such trouble? Nobody knows. The
brain seems to be making choices according to some stubborn timing
pattern, undoubtedly influenced by both culture and gene. This fact
suggests a teaching and business imperative: Find a way to arouse
and then hold somebody’s attention for a specific period of time. But

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how? To answer that question, we will need to explore some complex
pieces of neurological real estate. We are about to investigate the
remarkable world of human attention—including what’s going on in
our brains when we turn our attention to something, the importance
of emotions, and the myth of multitasking.
can i have your attention, please?
While you are reading this paragraph, millions of sensory neurons
in your brain are firing simultaneously, all carrying messages,
each attempting to grab your attention. Only a few will succeed in
breaking through to your awareness, and the rest will be ignored
either in part or in full. Incredibly, it is easy for you to alter this
balance, effortlessly granting airplay to one of the many messages you
were previously ignoring. (While still reading this sentence, can you
feel where your elbows are right now?) The messages that do grab
your attention are connected to memory, interest, and awareness.
memory
What we pay attention to is often profoundly influenced by
memory. In everyday life, we use previous experience to predict
where we should pay attention. Different environments create
different expectations. This was profoundly illustrated by the scientist
Jared Diamond in his book Guns, Germs, and Steel. He describes an
adventure traipsing through the New Guinea jungle with native
New Guineans. He relates that these natives tend to perform poorly
at tasks Westerners have been trained to do since childhood. But
they are hardly stupid. They can detect the most subtle changes in
the jungle, good for following the trail of a predator or for finding
the way back home. They know which insects to leave alone, know
where food exists, can erect and tear down shelters with ease.
Diamond, who had never spent time in such places, has no ability to
pay attention to these things. Were he to be tested on such tasks, he
also would perform poorly.

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Culture matters, too, even when the physical ecologies are
similar. For example, urban Asians pay a great deal of attention to the
context of a visual scene and to the relationships between foreground
objects and backgrounds. Urban Americans don’t. They pay attention
to the focal items before the backgrounds, leaving perceptions of
context much weaker. Such differences can affect how an audience
perceives a given business presentation or class lecture.
interest
Happily, there are some commonalities regardless of culture.
For example, we have known for a long time that “interest” or
“importance” is inextricably linked to attention. Researchers
sometimes call this arousal. Exactly how it relates to attention is still
a mystery. Does interest create attention? We know that the brain
continuously scans the sensory horizon, with events constantly
assessed for their potential interest or importance. The more
important events are then given extra attention. Can the reverse
occur, with attention creating interest?
Marketing professionals think so. They have known for years
that novel stimuli—the unusual, unpredictable, or distinctive—are
powerful ways to harness attention in the service of interest. One
well-known example is a print ad for Sauza Conmemorativo tequila.
It shows a single picture of an old, dirty, bearded man, donning a
brimmed hat and smiling broadly, revealing a single tooth. Printed
above the mouth is: “This man only has one cavity.” A larger sentence
below says: “Life is harsh. Your tequila shouldn’t be.” Flying in the
face of most tequila marketing strategies, which consist of scantily
clad 20-somethings dancing at a party, the ad is effective at using
attention to create interest.
awareness
Of course, we must be aware of something for it to grab
our attention. You can imagine how tough it is to research such

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an ephemeral concept. We don’t know the neural location of
consciousness, loosely defined as that part of the mind where
awareness resides. (The best data suggest that several systems are
scattered throughout the brain.) We have a long way to go before we
fully understand the biology behind attention.
One famous physician who has examined awareness at the
clinical level is Dr. Oliver Sacks, a delightful British neurologist
and one terrific storyteller. One of his most intriguing clinical cases
was first described in his bestselling book The Man Who Mistook His
Wife for a Hat. Sacks describes a wonderful older woman in his care,
intelligent, articulate, and gifted with a sense of humor. She suffered
a massive stroke in the back region of her brain that left her with a
most unusual deficit: She lost the ability to pay attention to anything
that was to her left. She could pick up objects only in the right half
of her visual field. She could put lipstick only on the right half of her
face. She ate only from the right half of her plate. This caused her
to complain to the hospital nursing staff that her portions were too
small! Only when the plate was turned and the food entered her right
visual field could she pay any attention to it and have her fill.
Data like these are very useful to both clinicians and scientists.
When damage occurs to a specific brain region, we know that any
observed behavioral abnormality must in some way be linked to
that region’s function. Examining a broad swath of patients like
Sacks’s gave scientists a cumulative view of how the brain pays
attention to things. The brain can be divided roughly into two
hemispheres of unequal function, and patients can get strokes in
either. Marcel Mesulam of Northwestern University found that the
hemispheres contain separate “spotlights” for visual attention. The
left hemisphere’s spotlight is small, capable of paying attention only
to items on the right side of the visual field. The right hemisphere,
however, has a global spotlight. According to Mesulam, getting a
stroke on the left side is much less catastrophic because the right side
can pitch in under duress to aid vision.

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Of course, sight is only one stimulus to which the brain is capable
of paying attention. Just let a bad smell into the room for a moment
or make a loud noise and people easily will shift attention. We also
pay close attention to our psychological interiors, mulling over
internal events and feelings again and again with complete focus,
with no obvious external sensory stimulation. What’s going on in our
heads when we turn our attention to something?
red alert
Thirty years ago, a scientist by the name of Michael Posner
derived a theory about attention that remains popular today. Posner
started his research career in physics, joining the Boeing Aircraft
Company soon out of college. His first major research contribution
was to figure out how to make jet-engine noise less annoying to
passengers riding in commercial airplanes. You can thank your
relatively quiet airborne ride, even if the screaming turbine is only
a few feet from your eardrums, in part on Posner’s first research
efforts. His work on planes eventually led him to wonder how the
brain processes information of any kind. This led him to a doctorate
in research and to a powerful idea. Sometimes jokingly referred to
as the Trinity Model, Posner hypothesized that we pay attention to
things because of the existence of three separable but fully integrated
systems in the brain.
One pleasant Saturday morning, my wife and I were sitting on
our outdoor deck, watching a robin drink from our birdbath, when
all of a sudden we heard a giant “swoosh” above our heads. Looking
up, we caught the shadow of a red-tailed hawk, dropping like a
thunderbolt from its perch in a nearby tree, grabbing the helpless
robin by the throat. As the raptor swooped by us, not 3 feet away,
blood from the robin splattered on our table. What started as a
leisurely repast ended as a violent reminder of the savagery of the
real world. We were stunned into silence.
In Posner’s model, the brain’s first system functions much like

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the two-part job of a museum security officer: surveillance and
alert. He called it the Alerting or Arousal Network. It monitors the
sensory environment for any unusual activities. This is the general
level of attention our brains are paying to our world, a condition
termed Intrinsic Alertness. My wife and I were using this network
as we sipped our coffee, watching the robin. If the system detects
something unusual, such as the hawk’s swoosh, it can sound an alarm
heard brain-wide. That’s when Intrinsic Alertness transforms into
specific attention, called Phasic Alertness.
After the alarm, we orient ourselves to the attending stimulus,
activating the second network. We may turn our heads toward the
stimulus, perk up our ears, perhaps move toward (or away) from
something. It’s why both my wife and I immediately lifted our heads
away from the robin, attending to the growing shadow of the hawk.
The purpose is to gain more information about the stimulus, allowing
the brain to decide what to do. Posner termed this the Orienting
Network.
The third system, the Executive Network, controls the “oh my
gosh what should I do now” behaviors. These may include setting
priorities, planning on the fly, controlling impulses, weighing the
consequences of our actions, or shifting attention. For my wife and
me, it was stunned silence.
So we have the ability to detect a new stimulus, the ability to turn
toward it, and the ability to decide what to do based on its nature.
Posner’s model offered testable predictions about brain function and
attention, leading to neurological discoveries that would fill volumes.
Hundreds of behavioral characteristics have since been discovered as
well. Four have considerable practical potential: emotions, meaning,
multitasking, and timing.
1) Emotions get our attention
Emotionally arousing events tend to be better remembered than
neutral events.

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While this idea may seem intuitively obvious, it’s frustrating to
demonstrate scientifically because the research community is still
debating exactly what an emotion is. One important area of research
is the effect of emotion on learning. An emotionally charged event
(usually called an ECS, short for emotionally competent stimulus)
is the best-processed kind of external stimulus ever measured.
Emotionally charged events persist much longer in our memories
and are recalled with greater accuracy than neutral memories.
This characteristic has been used to great effect, and sometimes
with great controversy, in television advertising. Consider a television
advertisement for the Volkswagen Passat. The commercial opens with
two men talking in a car. They are having a mildly heated discussion
about one of them overusing the word “like” in conversation. As the
argument continues, the viewer notices out the passenger window
another car barreling toward the men. It smashes into them. There
are screams, sounds of shattering glass, quick-cut shots showing the
men bouncing in the car, twisted metal. The exit shot shows the
men standing, in disbelief, outside their wrecked Volkswagen. In a
twist on a well-known expletive, these words flash on the screen:
“Safe Happens.” The spot ends with a picture of another Passat, this
one intact and complete with its five-star side-crash safety rating. It
is a memorable, even disturbing, 30-second spot. And it has these
characteristics because its centerpiece is an ECS.
How does this work in our brains? It involves the prefrontal
cortex, that uniquely human part of the brain that governs “executive
functions” such as problem-solving, maintaining attention, and
inhibiting emotional impulses. If the prefrontal cortex is the board
chairman, the cingulate gyrus is its personal assistant. The assistant
provides the chairman with certain filtering functions and assists
in teleconferencing with other parts of the brain—especially the
amygdala, which helps create and maintain emotions. The amygdala
is chock-full of the neurotransmitter dopamine, and it uses dopamine
the way an office assistant uses Post-It notes. When the brain detects

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an emotionally charged event, the amygdala releases dopamine into
the system. Because dopamine greatly aids memory and information
processing, you could say the Post-It note reads “Remember this!”
Getting the brain to put a chemical Post-It note on a given piece of
information means that information is going to be more robustly
processed. It is what every teacher, parent, and ad executive wants.
Emotionally charged events can be divided into two categories:
those that no two people experience identically, and those that
everybody experiences identically.
When my mother got angry (which was rare), she went to the
kitchen, washing LOUDLY any dishes she discovered in the sink.
And if there were pots and pans, she deliberately would crash them
together as she put them away. This noise served to announce to the
entire household (if not the city block) her displeasure at something.
To this day, whenever I hear loudly clanging pots and pans, I
experience an emotionally competent stimulus—a fleeting sense
of “You’re in trouble now!” My wife, whose mother never displayed
anger in this fashion, does not associate anything emotional with the
noise of pots and pans. It’s a uniquely stimulated, John-specific ECS.
Universally experienced stimuli come directly from our
evolutionary heritage, so they hold the greatest potential for use in
teaching and business. Not surprisingly, they follow strict Darwinian
lines of threats and energy resources. Regardless of who you are, the
brain pays a great deal of attention to these questions:
“Can I eat it? Will it eat me?”
“Can I mate with it? Will it mate with me?”
“Have I seen it before?”
Any of our ancestors who didn’t remember threatening
experiences thoroughly or acquire food adequately would not
live long enough to pass on his genes. The human brain has
many dedicated systems exquisitely tuned to reproductive
opportunity and to the perception of threat. (That’s why the
robbery story grabbed your attention—and why I put it at the

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beginning of this chapter.) We also are terrific pattern matchers,
constantly assessing our environment for similarities, and we
tend to remember things if we think we have seen them before.
One of the best TV spots ever made used all three principles in
an ever-increasing spiral. Stephen Hayden produced the commercial,
introducing the Apple computer in 1984. It won every major
advertising award that year and set a standard for Super Bowl ads.
The commercial opens onto a bluish auditorium filled with robot-
like men all dressed alike. In a reference to the 1956 movie 1984,
the men are staring at a screen where a giant male face is spouting
off platitude fragments such as “information purification!” and
“unification of thought!” The men in the audience are absorbing
these messages like zombies. Then the camera shifts to a young
woman in gym clothes, sledgehammer in hand, running full tilt
toward the auditorium. She is wearing red shorts, the only primary
color in the entire commercial. Sprinting down the center aisle, she
throws her sledgehammer at the screen containing Big Brother. The
screen explodes in a hail of sparks and blinding light. Plain letters
flash on the screen: “On January 24th
, Apple Computer will introduce
Macintosh. And you’ll see why 1984 won’t be like 1984.”
All of the elements are at work here. Nothing could be more
threatening to a country marinated in free speech than George
Orwell’s 1984 totalitarian society. There is sex appeal, with the
revealing gym shorts, but there is a twist. Mac is a female, so-o-o …
IBM must be a male. In the female-empowering 1980s, a whopping
statement on the battle of the sexes suddenly takes center stage.
Pattern matching abounds as well. Many people have read 1984 or
seen the movie. Moreover, people who were really into computers at
the time made the connection to IBM, a company often called Big
Blue for its suit-clad sales force.
2) Meaning before details
What most people remember about that commercial is its

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emotional appeal rather than every detail. There is a reason for that.
The brain remembers the emotional components of an experience
better than any other aspect. We might forget minute details of an
interstate fender bender, for example, yet vividly recall the fear of
trying to get to the shoulder without further mishap.
Studies show that emotional arousal focuses attention on the
“gist” of an experience at the expense of peripheral details. Many
researchers think that’s how memory normally works—by recording
the gist of what we encounter, not by retaining a literal record of
the experience. With the passage of time, our retrieval of gist always
trumps our recall of details. This means our heads tend to be filled
with generalized pictures of concepts or events, not with slowly
fading minutiae. I am convinced that America’s love of retrieval game
shows such as Jeopardy! exists because we are dazzled by the unusual
people who can invert this tendency.
Of course, at work and at school, detailed knowledge often is
critical for success. Interestingly, our reliance on gist may actually be
fundamental to finding a strategy for remembering details. We know
this from a fortuitous series of meetings that occurred in the 1980s
between a brain scientist and waiter.
Watching J.C. take an order is like watching Ken Jennings play
Jeopardy! J.C. never writes anything down, yet he never gets the order
wrong. As the menu offers more than 500 possible combinations
of food (entrees, side dishes, salad dressing, etc.) per customer, this
is an extraordinary achievement. J.C. has been recorded taking the
orders of 20 people consecutively with a zero percent error rate. J.C.
worked in a restaurant frequented by University of Colorado brain
scientist K. Anders Ericsson. Noticing how unusual J.C.’s skills were,
he asked J.C. if he would submit to being studied. The secret of J.C.’s
success lay in the deployment of a powerful organization strategy. He
always divided the customer’s order into discrete categories, such as
entree, temperature, side dish, and so on. He then coded the details
of a particular order using a lettering system. For salad dressing, Blue

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Cheese was always “B,” Thousand Island always “T” and so on. Using
this code with the other parts of the menu, he assigned the letters
to an individual face and remembered the assignment. By creating a
hierarchy of gist, he easily could apprehend the details.
J.C.’s strategy employs a principle well-known in the brain-science
community: Memory is enhanced by creating associations between
concepts. This experiment has been done hundreds of times, always
achieving the same result: Words presented in a logically organized,
hierarchical structure are much better remembered than words
placed randomly—typically 40 percent better. This result baffles
scientists to this day. Embedding associations between data points
necessarily increases the number of items to be memorized. More
pieces of intellectual baggage to inventory should make learning
more difficult. But that is exactly not what was found. If we can
derive the meaning of the words to one another, we can much more
easily recall the details. Meaning before details.
John Bransford, a gifted education researcher who edited the
well-received How People Learn, one day asked a simple question: In
a given academic discipline, what separates novices from experts?
Bransford eventually discovered six characteristics, one of which is
relevant to our discussion: “[Experts’] knowledge is not simply a list
of facts and formulas that are relevant to their domain; instead, their
knowledge is organized around core concepts or ‘big ideas’ that guide
their thinking about their domains.”
Whether you are a waiter or a brain scientist, if you want to get
the particulars correct, don’t start with details. Start with the key
ideas and, in a hierarchical fashion, form the details around these
larger notions.
3) The brain cannot multitask
Multitasking, when it comes to paying attention, is a myth. The
brain naturally focuses on concepts sequentially, one at a time. At first
that might sound confusing; at one level the brain does multitask.

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You can walk and talk at the same time. Your brain controls your
heartbeat while you read a book. Pianists can play a piece with left
hand and right hand simultaneously. Surely this is multitasking.
But I am talking about the brain’s ability to pay attention. It is the
resource you forcibly deploy while trying to listen to a boring lecture
at school. It is the activity that collapses as your brain wanders during
a tedious presentation at work. This attentional ability is not capable
of multitasking.
Recently, I agreed to help the high-school son of a friend of
mine with some homework, and I don’t think I will ever forget the
experience. Eric had been working for about a half-hour on his laptop
when I was ushered to his room. An iPod was dangling from his neck,
the earbuds cranking out Tom Petty, Bob Dylan, and Green Day as
his left hand reflexively tapped the backbeat. The laptop had at least
11 windows open, including two IM screens carrying simultaneous
conversations with MySpace friends. Another window was busy
downloading an image from Google. The window behind it had the
results of some graphic he was altering for MySpace friend No. 2, and
the one behind that held an old Pong game paused mid-ping.
Buried in the middle of this activity was a word-processing
program holding the contents of the paper for which I was to provide
assistance. “The music helps me concentrate,” Eric declared, taking
a call on his cell phone. “I normally do everything at school, but I’m
stuck. Thanks for coming.” Stuck indeed. Eric would make progress
on a sentence or two, then tap out a MySpace message, then see if the
download was finished, then return to his paper. Clearly, Eric wasn’t
concentrating on his paper. Sound like someone you know?
To put it bluntly, research shows that we can’t multitask. We
are biologically incapable of processing attention-rich inputs
simultaneously. Eric and the rest of us must jump from one thing to
the next.
To understand this remarkable conclusion, we must delve a little
deeper into the third of Posner’s trinity: the Executive Network. Let’s

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look at what Eric’s Executive Network is doing as he works on his
paper and then gets interrupted by a “You’ve got mail!” prompt from
his girlfriend, Emily.
step 1: shift alert
To write the paper from a cold start, blood quickly rushes to the
anterior prefrontal cortex in Eric’s head. This area of the brain, part
of the Executive Network, works just like a switchboard, alerting the
brain that it’s about to shift attention.
step 2: rule activation for task #1
Embedded in the alert is a two-part message, electricity sent
crackling throughout Eric’s brain. The first part is a search query to
find the neurons capable of executing the paper-writing task. The
second part encodes a command that will rouse the neurons, once
discovered. This process is called “rule activation,” and it takes several
tenths of a second to accomplish. Eric begins to write his paper.
step 3: disengagement
While he’s typing, Eric’s sensory systems picks up the email alert
from his girlfriend. Because the rules for writing a paper are different
from the rules for writing to Emily, Eric’s brain must disengage from
the paper-writing rules before he can respond. This occurs. The
switchboard is consulted, alerting the brain that another shift in
attention is about to happen.
step 4: rule activation for task #2
Another two-part message seeking the rule-activation protocols
for emailing Emily is now deployed. As before, the first is a command
to find the writing-Emily rules, and the second is the activation
command. Now Eric can pour his heart out to his sweetheart. As
before, it takes several tenths of a second simply to perform the
switch.

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Incredibly, these four steps must occur in sequence every time
Eric switches from one task to another. It is time-consuming. And it
is sequential. That’s why we can’t multitask. That’s why people find
themselves losing track of previous progress and needing to “start
over,” perhaps muttering things like “Now where was I?” each time
they switch tasks. The best you can say is that people who appear
to be good at multitasking actually have good working memories,
capable of paying attention to several inputs one at a time.
Here’s why this matters: Studies show that a person who is
interrupted takes 50 percent longer to accomplish a task. Not only
that, he or she makes up to 50 percent more errors.
Some people, particularly younger people, are more adept at task-
switching. If a person is familiar with the tasks, the completion time
and errors are much less than if the tasks are unfamiliar. Still, taking
your sequential brain into a multitasking environment can be like
trying to put your right foot into your left shoe.
A good example is driving while talking on a cell phone. Until
researchers started measuring the effects of cell-phone distractions
under controlled conditions, nobody had any idea how profoundly
they can impair a driver. It’s like driving drunk. Recall that large
fractions of a second are consumed every time the brain switches
tasks. Cell-phone talkers are a half-second slower to hit the brakes in
emergencies, slower to return to normal speed after an emergency,
and more wild in their “following distance” behind the vehicle in
front of them. In a half-second, a driver going 70 mph travels 51
feet. Given that 80 percent of crashes happen within three seconds
of some kind of driver distraction, increasing your amount of task-
switching increases your risk of an accident. More than 50 percent of
the visual cues spotted by attentive drivers are missed by cell-phone
talkers. Not surprisingly, they get in more wrecks than anyone except
very drunk drivers.
It isn’t just talking on a cell phone. It’s putting on makeup,
eating, rubber-necking at an accident. One study showed that simply

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reaching for an object while driving a car multiplies the risk of a
crash or near-crash by nine times. Given what we know about the
attention capacity of the human brain, these data are not surprising.
4) The brain needs a break
Our need for timed interruptions reminds me of a film called
Mondo Cane, which holds the distinction of being the worst movie
my parents reported ever seeing. Their sole reason for hating this
movie was one disturbing scene: farmers force-feeding geese to make
pâté de foie gras. Using fairly vigorous strokes with a pole, farmers
literally stuffed food down the throats of these poor animals. When
a goose wanted to regurgitate, a brass ring was fastened around its
throat, trapping the food inside the digestive tract. Jammed over and
over again, such nutrient oversupply eventually created a stuffed
liver, pleasing to chefs around the world. Of course, it did nothing
for the nourishment of the geese, who were sacrificed in the name of
expediency.
My mother would often relate this story to me when she talked
about being a good or bad teacher. “Most teachers overstuff their
students,” she would exclaim, “like those farmers in that awful
movie!” When I went to college, I soon discovered what she meant.
And now that I am a professor who has worked closely with the
business community, I can see the habit close up. The most common
communication mistakes? Relating too much information, with
not enough time devoted to connecting the dots. Lots of force-
feeding, very little digestion. This does nothing for the nourishment
of the listeners, whose learning is often sacrificed in the name of
expediency.
At one level, this is understandable. Most experts are so familiar
with their topic that they forget what it is like to be a novice. Even if
they remember, experts can become bored with having to repeat the
fundamentals over and over again. In college, I found that a lot of
my professors, because they had to communicate at such elementary

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levels, were truly fed up with teaching. They seemed to forget that
the information was brand new to us, and that we needed the time to
digest it, which meant a need for consistent breaks. How true indeed
that expertise doesn’t guarantee good teaching!
Such needs are not the case just in classrooms. I have observed
similar mistakes in sermons, boardrooms, sales pitches, media
stories—anywhere information from an expert needs to be
transferred to a novice.
ideas
The 10-minute rule provides a way out of these problems. Here’s
the model I developed for giving a lecture, for which I was named the
Hoechst Marion Rousell Teacher of the Year.
Lecture design: 10-minute segments
I decided that every lecture I’d ever give would come in discrete
modules. Since the 10-minute rule had been known for many years,
I decided the modules would last only 10 minutes. Each segment
would cover a single core concept—always large, always general,
always filled with “gist,” and always explainable in one minute. Each
class was 50 minutes, so I could easily burn through five large
concepts in a single period. I would use the other 9 minutes in the
segment to provide a detailed description of that single general
concept. The trick was to ensure that each detail could be easily
traced back to the general concept with minimal intellectual effort.
I regularly took time out from content to explain the relationship
between the detail and the core concept in clear and explicit terms.
It was like allowing the geese to rest between stuffings.
Then came the hardest part: After 10 minutes had elapsed, I had
to be finished with the core concept. Why did I construct it that way?
Three reasons:
1) Given the tendency of an audience to check out 20 percent

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of the way into a presentation, I knew I initially had only about
600 seconds to earn the right to be heard—or the next hour would
be useless. I needed to do something after the 601st
second to “buy”
another 10 minutes.
2) The brain processes meaning before detail. Providing the gist,
the core concept, first was like giving a thirsty person a tall glass of
water. And the brain likes hierarchy. Starting with general concepts
naturally leads to explaining information in a hierarchical fashion.
You have to do the general idea first. And then you will see that 40
percent improvement in understanding.
3) It’s key that the instructor explains the lecture plan at the
beginning of the class, with liberal repetitions of “where we are”
sprinkled throughout the hour. This prevents the audience from
trying to multitask. If the instructor presents a concept without
telling the audience where that concept fits into the rest of the
presentation, the audience is forced to simultaneously listen to the
instructor and attempt to divine where it fits into the rest of what
the instructor is saying. This is the pedagogical equivalent of trying
to drive while talking on a cell phone. Because it is impossible to
pay attention to ANY two things at once, this will cause a series of
millisecond delays throughout the presentation. The linkages must
be clearly and repetitively explained.
Bait the hook
After 9 minutes and 59 seconds, the audience’s attention is
getting ready to plummet to near zero. If something isn’t done
quickly, the students will end up in successively losing bouts of an
effort to stay with me. What do they need? Not more information of
the same type. That would be like geese choking on the food with no
real chance to digest. They also don’t need some completely irrelevant
cue that breaks them from their train of thought, making the

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information stream seem disjointed, unorganized, and patronizing.
They need something so compelling that they blast through the 10-
minute barrier and move on to new ground—something that triggers
an orienting response toward the speaker and captures executive
functions, allowing efficient learning.
Do we know anything so potentially compelling? We sure do. The
ECS—emotionally competent stimuli. So, every 10 minutes in my
lecture, I decided to give my audiences a break from the firehose of
information and send them a relevant ECS, which I now call “hooks.”
As I did more teaching, I found the most successful hooks always
followed these three principles:
1) The hook had to trigger an emotion. Fear, laughter, happiness,
nostalgia, incredulity—the entire emotional palette could be
stimulated, and all worked well. I deliberately employed Darwin
here, describing some threatening event or, with appropriate
taste, some reproductive event, even something triggering pattern
matching. Narratives can be especially strong, especially if they are
crisp and to the point.
2) The hook had to be relevant. It couldn’t be just any story or
anecdote. If I simply cracked a joke or delivered some irrelevant
anecdote every 10 minutes, the presentation seemed disjointed. Or
worse: The listeners began to mistrust my motives; they seemed to
feel as if I were trying to entertain them at the expense of providing
information. Audiences are really good at detecting disorganization,
and they can become furious if they feel patronized. Happily, I
found that if I made the hook very relevant to the provided content,
the group moved from feeling entertained to feeling engaged. They
stayed in the flow of my material, even though they were really
taking a break.
3) The hook had to go between modules. I could place it at

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the end of the 10 minutes, looking backward, summarizing the
material, repeating some aspect of content. Or I could place it at the
beginning of the module, looking forward, introducing new material,
anticipating some aspect of content. I found that starting a lecture
with a forward-looking hook relevant to the entire day’s material was
a great way to corral the attention of the class.
Exactly what did these hooks look like? This is where teaching
can truly become imaginative. Because I work with psychiatric issues,
case histories explaining some unusual mental pathology often rivet
students to the upcoming (and drier) material. Business-related
anecdotes can be fun, especially when addressing lay audiences in
the corporate world. I often illustrate a talk about how brain science
relates to business by addressing its central problem: vocabulary.
I like the anecdote of the Electrolux Vacuum Cleaner company, a
privately held corporation in Sweden trying to break into the North
American market. They had plenty of English speakers on staff, but
no Americans. Their lead marketing slogan? “If it sucks, it must be
an Electrolux.”
When I started placing hooks in my lectures, I immediately
noticed changes in the audience members’ attitudes. First, they
were still interested at the end of the first 10 minutes. Second, they
seemed able to maintain their attention for another 10 minutes or
so, as long as another hook was supplied at the end. I could win the
battle for their attention in 10-minute increments.
But then, halfway through the lecture, after I’d deployed two or
three hooks, I found I could skip the fourth and fifth ones and still
keep their attention fully engaged. I have found this to be true for
students in 1994, when I first used the model, and in my lectures to
this day.
Does that mean my model has harnessed the timing and power
of emotional salience in human learning? That teachers and business
professionals everywhere should drop whatever they are doing and
incorporate its key features? I have no idea, but it would make sense

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to find out. The brain doesn’t pay attention to boring things, and I
am as sick of boring presentations as you are.
Do one thing at a time
The brain is a sequential processor, unable to pay attention to two
things at the same time. Businesses and schools praise multitasking,
but research clearly shows that it reduces productivity and increases
mistakes. Try creating an interruption-free zone during the day—
turn off your e-mail, phone, IM program, or BlackBerry—and see
whether you get more done.

102. Summary
Rule #4
People don’t pay attention to boring things.
The brain’s attentional “spotlight” can focus on only
•
•
one thing at a time: no multitasking.
We are better at seeing patterns and abstracting the
•
•
meaning of an event than we are at recording detail.
Emotional arousal helps the brain learn.
•
•
Audiences check out after 10 minutes, but you can
•
•
keep grabbing them back by telling narratives or creating
events rich in emotion.
Get more at www.brainrules.net

103. short-term
memory
Rule #5
Repeat to remember.

105. it is the ultimate intellectual flattery to be born with a
mind so amazing that brain scientists voluntarily devote
their careers to studying it. This impressive feat occurred
with the owners of two such minds in the past century, and their
remarkable brains provide much insight into human memory.
The first mind belongs to Kim Peek. He was born in 1951 with not
one hint of his future intellectual greatness. He has an enlarged head,
no corpus callosum, and a damaged cerebellum. He could not walk
until age 4, and he can get catastrophically upset when he doesn’t
understand something, which is often. Diagnosing him in childhood
as mentally disabled, his doctors wanted to place him in a mental
institution. That didn’t happen, mostly because of the nurturing
efforts of Peek’s father, who recognized that his son also had some
very special intellectual gifts. One of those gifts is memory; Peek has
one of the most prodigious ever recorded. He can read two pages at
the same time, one with each eye, comprehending and remembering
perfectly everything contained in the pages. Forever.

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Though publicity shy, Peek’s dad once granted writer Barry
Morrow an interview with his son. It was conducted in a library,
where Peek demonstrated to Morrow a familiarity with literally every
book (and every author) in the building. He then started quoting
ridiculous—and highly accurate—amounts of sports trivia. After
a long discussion about the histories of certain United States wars
(Revolutionary to Vietnam), Morrow felt he had enough. He decided
right then and there to write a screenplay about this man. Which he
did: the Oscar-winning film Rain Man.
What is going on in the uneven brain of Kim Peek? Does his mind
belong in a cognitive freak show, or is it only an extreme example of
normal human learning? Something very important is occurring in
the first few moments his brain is exposed to information, and it’s
not so very different from what happens to the rest of us in the initial
moments of learning.
The first few moments of learning give us the ability to remember
something. The brain has different types of memory systems, many
operating in a semi-autonomous fashion. We know so little about
how they coordinate with each other that, to this date, memory is
not considered a unitary phenomenon. We know the most about
declarative memory, which involves something you can declare,
such as “The sky is blue.” This type of memory involves four steps:
encoding, storage, retrieval, and forgetting. This chapter is about the
first step. In fact, it is about the first few seconds of the first step.
They are crucial in determining whether something that is initially
perceived will also be remembered. Along the way, we will talk about
our second famous mind. This brain, belonging to a man the research
community called H.M., was legendary not for its extraordinary
capabilities but for its extraordinary inabilities. We will also talk
about the difference between bicycles and Social Security numbers.
memory and mumbo jumbo
Memory has been the subject of poets and philosophers for

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centuries. At one level, memory is like an invading army, allowing
past experiences to intrude continuously onto present life. That’s
fortunate. Our brains do not come fully assembled at birth, which
means that most of what we know about the world has to be either
experienced by us firsthand or taught to us secondhand. Our robust
memory can provide great survival advantages—it is in large part
why we’ve succeeded in overpopulating the planet. For a creature as
physically weak as humans (compare your fingernail with the claw
of even a simple cat, and weep with envy), not allowing experience
to shape our brains would have meant almost certain death in the
rough-and-tumble world of the open savannah.
But memory is more than a Darwinian chess piece. Most
researchers agree that its broad influence on our brains is what truly
makes us consciously aware. The names and faces of our loved ones,
our own personal tastes, and especially our awareness of those names
and faces and tastes, are maintained through memory. We don’t go
to sleep and then, upon awakening, have to spend a week relearning
the entire world. Memory does this for us. Even the single most
distinctive talent of human cognition, the ability to write and speak
in a language, exists because of active remembering. Memory, it
seems, makes us not only durable but also human.
Let’s look at how it works. When researchers want to measure
memory, they usually end up measuring retrieval. That’s because
in order to find out if somebody has committed something to
memory, you have to ask if he or she can recall it. So, how do people
recall things? Does the storage space carrying the record of some
experience just sit there twiddling its thumbs in our brains, waiting
for some command to trot out its contents? Can we investigate
storage separately from retrieval? It has taken more than a hundred
years of research just to get a glimmer of a definition of memory that
makes sense to a scientist. The story began in the 19th
century with
a German researcher who performed the first real science-based

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inquiry into human memory. He did the whole thing with his own
brain.
Hermann Ebbinghaus was born in 1850. As a young man, he
looked like a cross between Santa Claus and John Lennon, with
his bushy brown beard and round glasses. He is most famous for
uncovering one of the most depressing facts in all of education:
People usually forget 90 percent of what they learn in a class within
30 days. He further showed that the majority of this forgetting
occurs within the first few hours after class. This has been robustly
confirmed in modern times.
Ebbinghaus designed a series of experimental protocols with
which a toddler might feel at ease: He made up lists of nonsense
words, 2,300 of them. Each word consisted of three letters and a
consonant-vowel-consonant construction, such as TAZ, LEF, REN,
ZUG. He then spent the rest of his life trying to memorize lists of
these words in varying combinations and of varying lengths.
With the tenacity of a Prussian infantryman (which, for a short
time, he was), Ebbinghaus recorded for over 30 years his successes
and failures. He uncovered many important things about human
learning during this journey. He showed that memories have different
life spans. Some memories hang around for only a few minutes, then
vanish. Others persist for days or months, even for a lifetime. He also
showed that one could increase the life span of a memory simply by
repeating the information in timed intervals. The more repetition
cycles a given memory experienced, the more likely it was to persist
in his mind. We now know that the space between repetitions is
the critical component for transforming temporary memories into
more persistent forms. Spaced learning is greatly superior to massed
learning.
Ebbinghaus’s work was foundational. It was also incomplete. It
did not, for example, separate the notion of memory from retrieval—
the difference between learning something and recalling it later.
Go ahead and try to remember your Social Security number.

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Easy enough? Your retrieval commands might include things like
visualizing the last time you saw the card, or remembering the last
time you wrote down the number. Now try to remember how to
ride a bike. Easy enough? Hardly. You do not call up a protocol list
detailing where you put your foot, how to create the correct angle
for your back, where your thumbs are supposed to be. The contrast
proves an interesting point: One does not recall how to ride a bike
in the same way one recalls nine numbers in a certain order. The
ability to ride a bike seems quite independent from any conscious
recollection of the skill. You were consciously aware when you were
remembering your Social Security number, but not when riding a
bike. Do you need to have conscious awareness in order to experience
a memory? Or is there more than one type of memory?
The answer seemed clearer as more data came in. The answer to
the first question was no, which answered the second question. There
are at least two types of memories: memories that involve conscious
awareness and memories that don’t. This awareness distinction
gradually morphed into the idea that there were memories you could
declare and there were memories you could not declare. Declarative
memories are those that can be experienced in our conscious
awareness, such as “this shirt is green,” “Jupiter is a planet,” or even
a list of words. Nondeclarative memories are those that cannot be
experienced in our conscious awareness, such as the motor skills
necessary to ride a bike.
This does not explain everything about human memory. It does
not even explain everything about declarative memory. But the rigor
of Ebbinghaus gave future scientists their first real shot at mapping
behavior onto a living brain. Then a 9-year-old boy was knocked off
his bicycle, forever changing the way brain scientists thought about
memory.
where memories go
In his accident, H.M. suffered a severe head injury that left him

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with epileptic seizures. These seizures got worse with age, eventually
culminating in one major seizure and 10 blackout periods every seven
days. By his late 20s, H.M. was essentially dysfunctional, of potential
great harm to himself, in need of drastic medical intervention.
The desperate family turned to famed neurosurgeon William
Scoville, who decided that the problem lay within the brain’s
temporal lobe (the brain region roughly located behind your ears).
Scoville excised the inner surface of this lobe on both sides of the
brain. This experimental surgery greatly helped the epilepsy. It also
left H.M with a catastrophic memory loss. Since the day the surgery
was completed, in 1953, H.M. has been unable to convert a new
short-term memory into a long-term memory. He can meet you once
and then an hour or two later meet you again, with absolutely no
recall of the first visit.
He has lost the conversion ability Ebbinghaus so clearly described
in his research more than 50 years before.
Even more dramatically, H.M. can no longer recognize his own
face in the mirror. Why? As his face aged, some of his physical
features changed. But, unlike the rest of us, H.M. cannot take this
new information and convert it into a long-term form. This leaves
him more or less permanently locked into a single idea about his
appearance. When he looks in the mirror and does not see this single
idea, he cannot identify to whom the image actually belongs.
As horrible as that is for H.M., it is of enormous value to the
research community. Because researchers knew precisely what
was taken from the brain, it was easy to map which brain regions
controlled the Ebbinghaus behaviors. A great deal of credit for this
work belongs to Brenda Milner, a psychologist who spent more than
40 years studying H.M. and laid the groundwork for much of our
understanding about the nerves behind memory. Let’s review for a
moment the biology of the brain.
You recall the cortex—that wafer-thin layer of neural tissue that’s
about the size of a baby blanket when unfurled. It is composed of six

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discrete layers of cells. It’s a busy place. Those cells process signals
originating from many parts of the body, including those lassoed by
your sense organs. They also help create stable memories, and that’s
where H.M.’s unfortunate experience becomes so valuable. Some
of H.M.’s cortex was left perfectly intact; other regions, such as his
temporal lobe, sustained heavy damage. It was a gruesome but ideal
opportunity for studying how human memory forms.
This baby blanket doesn’t just lay atop the brain, of course.
As if the blanket were capable of growing complex, sticky root
systems, the cortex adheres to the deeper structures of the brain
by a hopelessly incomprehensible thicket of neural connections.
One of the most important destinations of these connections is the
hippocampus, which is parked near the center of your brain, one
in each hemisphere. The hippocampus is specifically involved in
converting short-term information into longer-term forms. As you
might suspect, it is the very region H.M. lost during his surgery.
The anatomical relationship between the hippocampus and the
cortex has helped 21st
-century scientists further define the two types
of memory. Declarative memory is any conscious memory system
that is altered when the hippocampus and various surrounding
regions become damaged. Non-declarative memory is defined as
those unconscious memory systems that are NOT altered (or at least
not greatly altered) when the hippocampus and surrounding regions
are damaged. We’re going to focus on declarative memory, a vital part
of our everyday activities.
sliced and diced
Research shows that the life cycle of declarative memory can be
divided into four sequential steps: encoding, storing, retrieving, and
forgetting.
Encoding describes what happens at the initial moment of
learning, that fleeting golden instant when the brain first encounters
a new piece of declarative information. It also involves a whopping

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fallacy, one in which your brain is an active co-conspirator. Here’s
an example of this subversion, coming once again from the clinical
observations of neurologist Oliver Sacks.
The case involves a low-functioning autistic boy named Tom,
who has become quite famous for being able to “do” music (though
little else). Tom never received formal instruction in music of any
kind, but he learned to play the piano simply by listening to other
people. Astonishingly, he could play complex pieces of music with
the skill and artistry of accomplished professionals, on his first try
after hearing the music exactly once. In fact, he has been observed
playing the song “Fisher’s Horn Pipe” with his left hand while
simultaneously playing “Yankee Doodle Dandy” with his right hand
while simultaneously singing “Dixie”! He also can play the piano
backwards, that is, with his back to the keyboard and his hands
inverted. Not bad for a boy who cannot even tie his own shoes.
When we hear about people like this, we are usually jealous.
Tom absorbs music as if he could switch to the “on” position some
neural recording device in his head. We think we also have this video
recorder, only our model is not nearly as good. This is a common
impression. Most people believe that the brain is a lot like a recording
device—that learning is something akin to pushing the “record”
button (and remembering is simply pushing “playback”). Wrong.
In the real world of the brain—Tom’s or yours—nothing could be
further from the truth. The moment of learning, of encoding, is so
mysterious and complex that we have no metaphor to describe what
happens to our brains in those first fleeting seconds.
The little we do know suggests it is like a blender left running
with the lid off. The information is literally sliced into discrete
pieces as it enters the brain and splattered all over the insides of our
mind. Stated formally, signals from different sensory sources are
registered in separate brain areas. The information is fragmented and
redistributed the instant the information is encountered. If you look
at a complex picture, for example, your brain immediately extracts

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the diagonal lines from the vertical lines and stores them in separate
areas. Same with color. If the picture is moving, the fact of its motion
will be extracted and stored in a place separate than if the picture
were static.
This separation is so violent, and so pervasive, it even shows up
when we perceive exclusively human-made information, such as
parts of a language. One woman suffered a stroke in a specific region
of her brain and lost the ability to use written vowels. You could ask
her to write down a simple sentence, such as “Your dog chased the
cat,” and it would look like this:
Y_ _ r d _ g ch _ s _ d t h _ c _ t.
There would be a place for every letter, but the vowels’ spots were
left blank! So we know that vowels and consonants are not stored in
the same place. Her stroke damaged some kind of connecting wiring.
That is exactly the opposite of the strategy a video recorder uses to
record things. If you look closely, however, the blender effect goes
much deeper. Even though she lost the ability to fill in the vowels of
a given word, she has perfectly preserved the place where the vowel
should go. Using the same logic, it appears that the place where a
vowel should go is stored in a separate area from the vowel itself:
Content is stored separately from its context/container.
Hard to believe, isn’t it? The world appears to you as a unified
whole. If the interior brain function tells us that it is not, how then
do we keep track of everything? How do features that are registered
separately, including the vowels and consonants in this sentence,
become reunited to produce perceptions of continuity? It is a
question that has bothered researchers for years and has been given
its own special name. It is called the “binding problem,” from the
idea that certain thoughts are bound together in the brain to provide
continuity. We have no idea how the brain routinely and effortlessly
gives us this illusion of stability.

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Not that there aren’t hints. Close inspection of the initial
moments of learning, the encoding stage, has supplied insights into
not only the binding problem, but human learning of any kind. It is
to these hints that we now turn.
automatic or stick shift?
To encode information means to convert data into, well, a code.
Creating codes always involves translating information from one
form into another, usually for transmission purposes, often to keep
something secret. From a physiological point of view, encoding is the
conversion of external sources of energy into electrical patterns the
brain can understand. From a purely psychological point of view, it is
the manner in which we apprehend, pay attention to, and ultimately
organize information for storage purposes. Encoding, from both
perspectives, prepares information for further processing. It is one of
the many intellectual processes the Rain Man, Kim Peek, is so darn
good at.
The brain is capable of performing several types of encoding. One
type of encoding is automatic, which can be illustrated by talking
about what you had for dinner last night, or The Beatles. The two
came together for me on the evening of an amazing Paul McCartney
concert I attended a few years ago. If you were to ask me what I
had for dinner before the concert and what happened on stage, I
could tell you about both events in great detail. Though the actual
memory is very complex (composed of spatial locations, sequences of
events, sights, smells, tastes, etc.), I did not have to write down some
exhaustive list of its varied experiences, then try to remember the list
in detail just in case you asked me about my evening. This is because
my brain deployed a certain type of encoding scientists call automatic
processing. It is the kind occurring with glorious unintentionality,
requiring minimal attentional effort. It is very easy to recall data that
have been encoded via this process. The memories seem bound all
together into a cohesive, readily retrievable form.

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Automatic processing has an evil twin that isn’t nearly so
accommodating, however. As soon as the Paul McCartney tickets
went on sale, I dashed to the purchasing website, which required
my password for entrance. And I couldn’t remember my password!
Finally, I found the right one and snagged some good seats. But
trying to commit these passwords to memory is quite a chore, and
I have a dozen or so passwords written on countless lists, scattered
throughout my house. This kind of encoding, initiated deliberately,
requiring conscious, energy-burning attention, is called effortful
processing. The information does not seem bound together well at
all, and it requires a lot of repetition before it can be retrieved with
the ease of automatic processing.
encoding test
There are still other types of encoding, three of which can be
illustrated by taking the quick test below. Examine the capitalized
word beside the number, then answer the question below it.
1) FOOTBALL
Does this word fit into the sentence “I turned around to fight
_________”?
2) LEVEL
Does this word rhyme with evil?
3) MINIMUM
Are there any circles in these letters?
Answering each question requires very different intellectual
skills, which researchers now know underlie different types of
encoding. The first sentence illustrates what is called semantic
encoding. Answering the question properly means paying attention
to the definitions of words. The second sentence illustrates a process

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called phonemic encoding, involving a comparison between the
sounds of words. The third is called structural encoding. It is the
most superficial type, and it simply asks for a visual inspection
of shapes. The type of encoding you perform on a given piece of
information as it enters your head has a great deal to do with your
ability to remember the information at a later date.
the electric slide
Encoding also involves transforming any outside stimulus into
the electrical language of the brain, a form of energy transfer. All
types of encoding initially follow the same pathway, and generally the
same rules. For example, the night of Sir Paul’s concert, I stayed with
a friend who owned a beautiful lake cabin inhabited by a very large
and hairy dog. Late next morning, I decided to go out and play fetch
with this friendly animal. I made the mistake of throwing the stick
into the lake and, not owning a dog in those days, had no idea what
was about to happen to me when the dog emerged.
Like some friendly sea monster from Disney, the dog leapt from
the water, ran at me full speed, suddenly stopped, then started to
shake violently. With no real sense that I should have moved, I got
sopping wet.
What was occurring in my brain in those moments? As you know,
the cortex quickly is consulted when a piece of external information
invades our brains—in this case, a slobbery, soaking wet Labrador. I
see the dog coming out of the lake, which really means I see patterns
of photons bouncing off the Labrador. The instant those photons
hit the back of my eyes, my brain converts them into patterns of
electrical activity and routes the signals to the back of my head (the
visual cortex in the occipital lobe). Now my brain can see the dog. In
the initial moments of this learning, I have transformed the energy
of light into an electrical language the brain fully understands.
Beholding this action required the coordinated activation of
thousands of cortical regions dedicated to visual processing.

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The same is also true of other energy sources. My ears pick up the
sound waves of the dog’s loud bark, and I convert them into the same
brain-friendly electrical language to which the photons patterns were
converted. These electrical signals will also be routed to the cortex,
but to the auditory cortex instead of the visual cortex. From a nerve’s
perspective, those two centers are a million miles away from each
other. This conversion and this vastly individual routing are true of
all the energy sources coming into my brain, from the feel of the sun
on my skin to the instant I unexpectedly and unhappily got soaked by
the dog shaking off lake water. Encoding involves all of our senses,
and their processing centers are scattered throughout the brain.
This is the heart of the blender. In one 10-second encounter with
an overly friendly dog, my brain recruited hundreds of different brain
regions and coordinated the electrical activity of millions of neurons.
My brain was recording a single episode, and doing so over vast
neural differences, all in about the time it takes to blink your eyes.
Years have passed since I saw Sir Paul and got drenched by the
dog. How do we keep track of it all? And how do we manage to
manage these individual pieces for years? This binding problem,
a phenomenon that keeps tabs on farflung pieces of information,
is a great question with, unfortunately, a lousy answer. We really
don’t know how the brain keeps track of things. We have given a
name to the total number of changes in the brain that first encode
information (where we have a record of that information). We call
it an engram. But we might as well call them donkeys for all we
understand about them.
The only insight we have into the binding problem comes from
studying the encoding abilities of a person suffering from Balint’s
Syndrome. This disorder occurs in people who have damaged both
sides of their parietal cortex. The hallmark of people with Balint’s
Syndrome is that they are functionally blind. Well, sort of. They can
see objects in their visual field, but only one at a time (a symptom
called simultanagnosia). Funny thing is, if you ask them where the

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single object is, they respond with a blank stare. Even though they
can see it, they cannot tell you where it is. Nor can they tell you if
the object is moving toward them or away from them. They have no
external spatial frame of reference upon which to place the objects
they see, no way to bind the image to other features of the input.
They’ve lost explicit spatial awareness, a trait needed in any type of
binding exercise. That’s about as close as anyone has ever come to
describing the binding problem at the neurological level. This tells us
very little about how the brain solves the problem, of course. It only
tells us about some of the areas involved in the process.
cracking the code
Despite their wide reach, scientists have found that all encoding
processes have common characteristics. Three of these hold true
promise for real-world applications in both business and education.
1) The more elaborately we encode information at the moment
of learning, the stronger the memory.
When encoding is elaborate and deep, the memory that forms is
much more robust than when encoding is partial and cursory. This
can be demonstrated in an experiment you can do right now with
any two groups of friends. Have them gaze at the list of words below
for a few minutes.
Tractor Pastel Airplane
Green Quickly Jump
Apple Ocean Laugh
Zero Nicely Tall
Weather Countertop
Tell Group #1 to determine the number of letters that have
diagonal lines in them and the number that do not. Tell Group #2 to
think about the meaning of each word and rate, on a scale of 1 to 10,

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how much they like or dislike the word. Take the list away, let a few
minutes pass, and then ask each group to write down as many words
as possible. The dramatic results you get have been replicated in
laboratories around the world. The group that processes the meaning
of the words always remembers two to three times as many words
as the group that looked only at the architecture of the individual
letters. We did a form of this experiment when we discussed levels
of encoding and I asked you about the number of circles in the word
… remember what it was? You can do a similar experiment using
pictures. You can even do it with music. No matter the sensory input,
the results are always the same.
At this point, you might be saying to yourself, “Well, duh!” Isn’t it
obvious that the more meaning something has, the more memorable
it becomes? Most researchers would answer, “Well, yeah!” The very
naturalness of the tendency proves the point. Hunting for diagonal
lines in the word “apple” is not nearly as elaborate as remembering
wonderful Aunt Mabel’s apple pie, then rating the pie, and thus the
word, a “10.” We remember things much better the more elaborately
we encode what we encounter, especially if we can personalize it.
The trick for business professionals, and for educators, is to present
bodies of information so compelling that the audience does this on
their own, spontaneously engaging in deep and elaborate encoding.
It’s a bit weird if you think about it. Making something more
elaborate usually means making it more complicated, which should
be more taxing to a memory system. But it’s a fact: More complexity
means greater learning.
2) A memory trace appears to be stored in the same parts of the
brain that perceived and processed the initial input.
This idea is so counterintuitive that it may take an urban legend
to explain it. At least, I think it’s an urban legend, coming from the
mouth of the keynote speaker at a university administrators’ luncheon
I once attended. He told the story of the wiliest college president he

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ever encountered. The institute had completely redone its grounds in
the summer, resplendent with fountains and beautifully manicured
lawns. All that was needed was to install the sidewalks and walkways
where the students could access the buildings. But there was no
design for these paths. The construction workers were anxious to
install them and wanted to know what the design would be, but the
wily president refused to give any. He frowned. “These asphalt paths
will be permanent. Install them next year, please. I will give you the
plans then.” Disgruntled but compliant, the construction workers
waited.
The school year began, and the students were forced to walk
on the grass to get to their classes. Very soon, defined trails started
appearing all over campus, as well as large islands of beautiful green
lawn. By the end of the year, the buildings were connected by paths
in a surprisingly efficient manner. “Now,” said the president to the
contractors who had waited all year, “you can install the permanent
sidewalks and pathways. But you need no design. Simply fill in all the
paths you see before you!” The initial design, created by the initial
input, also became the permanent path.
The brain has a storage strategy remarkably similar to the wily
president’s plan. The neural pathways initially recruited to process
new information end up becoming the permanent pathways the
brain reuses to store the information. New information penetrating
into the brain can be likened to the students initially creating the dirt
paths across a pristine lawn. The final storage area can be likened to
the time those pathways were permanently filled with asphalt. They
are the same pathways, and that’s the point.
What does this mean for the brain? The neurons in the cortex are
active responders in any learning event, and they are deeply involved
in permanent memory storage. This means the brain has no central
happy hunting ground where memories go to be infinitely retrieved.
Instead, memories are distributed all over the surface of the cortex.
This may at first seem hard to grasp. Many people would like the

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brain to act like a computer, complete with input detectors (like a
keyboard) connected to a central storage device. Yet the data suggest
that the human brain has no hard drive separate from its initial input
detectors. That does not mean memory storage is spread evenly
across the brain’s neural landscape. Many brain regions are involved
in representing even single inputs, and each region contributes
something different to the entire memory. Storage is a cooperative
event.
3) Retrieval may best be improved by replicating the conditions
surrounding the initial encoding.
In one of the most unusual experiments performed in cognitive
psychology, the brain function of people standing around on dry
ground in wet suits was compared with the brain function of people
floating in about 10 feet of water, also in wet suits. Both groups of
deep-sea divers listened to somebody speak 40 random words. The
divers were then tested for their ability to recall the list of words.
The group that heard the words while in the water got a 15 percent
better score if they were asked to recall the words while back in those
same 10 feet than if they were on the beach. The group that heard
the words on the beach got a 15 percent better score if they were
asked to recall the words while suited on the beach than if in 10 feet
of water. It appeared that memory worked best if the environmental
conditions at retrieval mimicked the environmental conditions at
encoding. Is it possible that the second characteristic, which tries
to store events using the same neurons recruited initially to encode
events, is in operation in this third characteristic?
The tendency is so robust that memory is even improved under
conditions where learning of any kind should be crippled. These
experiments have been done incorporating marijuana and even
laughing gas (nitrous oxide). This third characteristic even responds
to mood. Learn something while you are sad and you will be able
to recall it better if, at retrieval, you are somehow suddenly made

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sad. The condition is called context-dependent or state-dependent
learning.
ideas
We know that information is remembered best when it is
elaborate, meaningful, and contextual. The quality of the encoding
stage—those earliest moments of learning—is one of the single
greatest predictors of later learning success. What can we do to take
advantage of that in the real world?
First, we can take a lesson from a shoe store I used to visit as a
little boy. This shoe store had a door with three handles at different
heights: one near the very top, one near the very bottom, and one
in the middle. The logic was simple: The more handles on the door,
the more access points were available for entrance, regardless of the
strength or age of customer. It was a relief for a 5-year-old—a door
I could actually reach! I was so intrigued with the door that I used
to dream about it. In my dreams, however, there were hundreds of
handles, all capable of opening the door to this shoe store.
“Quality of encoding” really means the number of door handles
one can put on the entrance to a piece of information. The more
handles one creates at the moment of learning, the more likely the
information is to be accessed at a later date. The handles we can add
revolve around content, timing, and environment.
Real-world examples
The more a learner focuses on the meaning of the presented
information, the more elaborately the encoding is processed. This
principle is so obvious that it is easy to miss. What it means is
this: When you are trying to drive a piece of information into your
brain’s memory systems, make sure you understand exactly what
that information means. If you are trying to drive information into
someone else’s brain, make sure they know what it means.
The directive has a negative corollary. If you don’t know what the

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learning means, don’t try to memorize the information by rote and
pray the meaning will somehow reveal itself. And don’t expect your
students will do this either, especially if you have done an inadequate
job of explaining things. This is like looking at the number of diagonal
lines in a word and attempting to use this strategy to remember the
words.
How does one communicate meaning in such a fashion that
learning is improved? A simple trick involves the liberal use
of relevant real-world examples embedded in the information,
constantly peppering main learning points with meaningful
experiences. This can be done by the learner studying after class or,
better, by the teacher during the actual learning experience. This has
been shown to work in numerous studies.
In one experiment, groups of students read a 32-paragraph paper
about a fictitious foreign country. The introductory paragraphs in the
paper were highly structured. They contained either no examples,
one example, or two or three consecutive examples of the main
theme that followed. The results were clear: The greater the number
of examples in the paragraph, the more likely the information was to
be remembered. It’s best to use real-world situations familiar to the
learner. Remember wonderful Aunt Mabel’s apple pie? This wasn’t an
abstract food cooked by a stranger; it was real food cooked by a loving
relative. The more personal an example, the more richly it becomes
encoded and the more readily it is remembered.
Why do examples work? They appear to take advantage of the
brain’s natural predilection for pattern matching. Information is
more readily processed if it can be immediately associated with
information already present in the learner’s brain. We compare the
two inputs, looking for similarities and differences as we encode the
new information. Providing examples is the cognitive equivalent
of adding more handles to the door. Providing examples makes the
information more elaborative, more complex, better encoded, and
therefore better learned.

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Compelling introductions
Introductions are everything. As an undergraduate, I had a
professor who can thoughtfully be described as a lunatic. He taught
a class on the history of cinema, and one day he decided to illustrate
for us how art films traditionally depict emotional vulnerability. As
he went through the lecture, he literally began taking off his clothes.
He first took off his sweater and then, one button at a time, began
removing his shirt, down to his T-shirt. He unzipped his trousers,
and they fell around his feet, revealing, thank goodness, gym clothes.
His eyes were shining as he exclaimed, “You will probably never
forget now that some films use physical nudity to express emotional
vulnerability. What could be more vulnerable than being naked?” We
were thankful that he gave us no further details of his example.
I will never forget the introduction to this unit in my film class,
though I hardly recommend imitating his example on a regular basis.
But its memorability illustrates the timing principle: If you are a
student, whether in business or education, the events that happen
the first time you are exposed to a given information stream play a
disproportionately greater role in your ability to accurately retrieve it
at a later date. If you are trying to get information across to someone,
your ability to create a compelling introduction may be the most
important single factor in the later success of your mission.
Why this emphasis on the initial moments? Because the memory
of an event is stored in the same places that were initially recruited
to perceive the learning event. The more brain structures recruited—
the more door handles created—at the moment the learning, the
easier it is to gain access to the information.
Other professions have stumbled onto this notion. Budding
directors are told by their film instructors that the audience needs
to be hooked in the first 3 minutes after the opening credits to make
the film compelling (and financially successful). Public speaking
professionals say that you win or lose the battle to hold your audience
in the first 30 seconds of a given presentation.

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What does that mean for business professionals attempting
to create a compelling presentation? Or educators attempting
to introduce a complex new topic? Given the importance of the
findings to the success of these professions, you might expect that
some rigorous scientific literature exists on this topic. Surprisingly,
very little data exist about how brains pay attention to issues in real-
world settings, as we discussed in the Attention chapter. The data
that do exist suggest that film instructors and public speakers are on
to something.
Familiar settings
We know the importance of learning and retrieval taking place
under the same conditions, but we don’t have a solid definition of
“same conditions.” There are many ways to explore this idea.
I once gave a group of teachers advice about how to counsel
parents who wanted to teach both English and Spanish at home. One
dissatisfying finding is that for many kids with this double exposure,
language acquisition rates for both go down, sometimes considerably.
I recounted the data about the underwater experiments and then
suggested that the families create a “Spanish Room.” This would be
a room with a rule: Only the Spanish language could be spoken in it.
The room could be filled with Hispanic artifacts, with large pictures
of Spanish words. All Spanish would be taught there, and no English.
Anecdotally, the parents have told me that it works.
This way, the encoding environments and retrieving
environments could be equivalent. At the moment of learning, many
environmental features—even ones irrelevant to the learning goals—
may become encoded into the memory right along with the goals.
Environment makes the encoding more elaborate, the equivalent of
putting more handles on the door. When these same environmental
cues are encountered, they may lead directly to the learning goals
simply because they were embedded in the original trace.
American marketing professionals have known about this

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phenomenon for years. What if I wrote the words “wind-up pink
bunny,” “pounding drum,” and “going-and-going,” then told you to
write another word or phrase congruent with those previous three?
No formal relationship exists between any of these words, yet if
you lived in the United States for a long period of time, most of you
probably would write words such as “battery” or “Energizer.” Enough
said.
What does it mean to make encoding and retrieving
environments equivalent in the real world of business and education?
The most robust findings occur when the environments exist in
dramatically different contexts from the norm (underwater vs. on a
beach is about as dramatic as it gets). But how different from normal
life does the setup need to be to obtain the effect?
It could be as simple as making sure that an oral examination
is studied for orally, rather than by reviewing written material. Or
perhaps future airplane mechanics should be taught about engine
repair in the actual shop where the repairs will occur.

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Summary
Rule #5
Repeat to remember.
The brain has many types of memory systems. One
•
•
type follows four stages of processing: encoding, storing,
retrieving, and forgetting.
Information coming into your brain is immediately split
•
•
into fragments that are sent to different regions of the
cortex for storage.
Most of the events that predict whether something
•
•
learned also will be remembered occur in the first few
seconds of learning.The more elaborately we encode a
memory during its initial moments, the stronger it will be.
You can improve your chances of remembering
•
•
something if you reproduce the environment in which you
first put it into your brain.
Get more at www.brainrules.net

129. long-term
memory
Rule #6
Remember to repeat.

131. for many years, textbooks described the birth of a
memory using a metaphor involving cranky dockworkers,
a large bookstore, and a small loading dock. An event to
be processed into memory was likened to somebody dropping off a
load of books onto the dock. If a dockworker hauled the load into the
vast bookstore, it became stored for a lifetime. Because the loading
dock was small, only a few loads could be processed at any one time.
If someone dumped a new load of books on the dock before the
previous ones were removed, the cranky workers simply pushed the
old ones over the side.
Nobody uses this metaphor anymore, and there are ample
reasons to wish it good riddance. Short-term memory is a much
more active, much less sequential, far more complex process than
the metaphor suggests. We now suspect that short-term memory is
actually a collection of temporary memory capacities. Each capacity
specializes in processing a specific type of information. Each operates
in a parallel fashion with the others. To reflect this multifaceted

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talent, short-term memory is now called working memory. Perhaps
the best way to explain working memory is to describe it in action.
I can think of no better illustration than the professional chess
world’s first real rock star: Miguel Najdorf. Rarely was a man more at
ease with his greatness than Najdorf. He was a short, dapper fellow
gifted with a truly enormous voice, and he had an annoying tendency
to poll members of his audience on how they thought he was doing.
Najdorf in 1939 traveled to a competition in Buenos Aires with the
national team. Two weeks later, Germany invaded Najdorf’s home
country of Poland. Unable to return, Najdorf rode out the Holocaust
tucked safely inside Argentina. He lost his parents, four brothers, and
his wife to the concentration camps. In hopes that any remaining
family might read about it and contact him, he once played 45 games
of chess simultaneously, as a publicity stunt. He won 39 of these
games, drew 4, and lost 2. While that is amazing in its own right, the
truly phenomenal part is that he played all 45 games in all 11 hours
blindfolded.
You did not read that wrong. Najdorf never physically saw any of
the chessboards or pieces; he played each game in his mind. From the
verbal information he received with each move, to his visualizations
of each board, several components of working memory were working
simultaneously in Najdorf’s mind. This allowed him to function in
his profession, just as they do in yours and mine (though perhaps
with a slightly different efficiency).
Working memory is now known to be a busy, temporary
workspace, a desktop the brain uses to process newly acquired
information. The man most associated with characterizing it is Alan
Baddeley, a British scientist who looks unnervingly like the angel
Clarence Oddbody in the movie It’s a Wonderful Life. Baddeley is most
famous for describing working memory as a three-component model:
auditory, visual, and executive.
The first component allows us to retain some auditory
information, and it is assigned to information that is linguistic.

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Baddeley called it a phonological loop. Najdorf was able to use this
component because his opponents were forced to declare their
moves verbally.
The second component allows us to retain some visual
information; this memory register is assigned to any images and
spatial input the brain encounters. Baddeley called it a visuo-spatial
sketchpad. Najdorf would have used it as he visualized each game.
The third component is a controlling function called the central
executive, which keeps track of all activities throughout working
memory. Najdorf used this ability to separate one game from another.
In later publications, Baddeley proposed a fourth component,
called the episodic buffer, assigned to any stories a person might
hear. This buffer has not been investigated extensively. Regardless
of the number of parallel systems ultimately discovered, researchers
agree that all share two important characteristics: All have a limited
capacity, and all have a limited duration. If the information is not
transformed into a more durable form, it will soon disappear. As
you recall, our friend Ebbinghaus was the first to demonstrate the
existence of two types of memory systems, a short form and a long
form. He further demonstrated that repetition could convert one into
the other under certain conditions. The process of converting short-
term memory traces to longer, sturdier forms is called consolidation.
consolidation
At first, a memory trace is flexible, labile, subject to amendment,
and at great risk for extinction. Most of the inputs we encounter in
a given day fall into this category. But some memories stick with us.
Initially fragile, these memories strengthen with time and become
remarkably persistent. They eventually reach a state where they
appear to be infinitely retrievable and resistant to amendment.
As we shall see, however, they may not be as stable as we think.
Nonetheless, we call these forms long-term memories.
Like working memory, there appear to be different forms of

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long-term memory, most of which interact with one another. Unlike
working memory, however, there is not as much agreement as to
what those forms are. Most researchers believe there are semantic
memory systems, which tend to remember things like your Aunt
Martha’s favorite dress or your weight in high school. Most also
believe there is episodic memory, in charge of remembering
“episodes” of past experiences, complete with characters, plots, and
time stamps (like your 25th
high school reunion). One of its subsets is
autobiographical memory, which features a familiar protagonist: you.
We used to think that consolidation, the mechanism that guides this
transformation into stability, affected only newly acquired memories.
Once the memory hardened, it never returned to its initial fragile
condition. We don’t think that anymore.
Consider the following story, which happened while I was
watching a TV documentary with my then 6-year-old son. It was
about dog shows. When the camera focused on a German shepherd
with a black muzzle, an event that occurred when I was about his age
came flooding back to my awareness.
In 1960, our backyard neighbor owned a dog he neglected to feed
every Saturday. In response to hunger cues, the dog bounded over
our fence precisely at 8 a.m. every Saturday, ran toward our metal
garbage cans, tipped out the contents, and began a morning repast.
My dad got sick of this dog and decided one Friday night to electrify
the can in such fashion that the dog would get shocked if his wet
little nose so much as brushed against it. Next morning, my dad
awakened our entire family early to observe his “hot dog” show. To
Dad’s disappointment, the dog didn’t jump over the fence until about
8:30, and he didn’t come to eat. Instead he came to mark his territory,
which he did at several points around our backyard. As the dog
moved closer to the can, my Dad started to smile, and when the dog
lifted his leg to mark our garbage can, my Dad exclaimed, “Yes!” You
don’t have to know the concentration of electrolytes in mammalian
urine to know that when the dog marked his territory on our garbage

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can, he also completed a mighty circuit. His cranial neurons ablaze,
his reproductive future suddenly in serious question, the dog howled,
bounding back to his owner. The dog never set foot in our backyard
again; in fact, he never came within 100 yards of our house. Our
neighbor’s dog was a German shepherd with a distinct black muzzle,
just like the one in the television show I was now watching. I had not
thought of the incident in years.
What physically happened to my dog memory when summoned
back to awareness? There is increasing evidence that when
previously consolidated memories are recalled from long-term
storage into consciousness, they revert to their previously labile,
unstable natures. Acting as if newly minted into working memory,
these memories may need to become reprocessed if they are to
remain in a durable form. That means the hot dog story is forced
to restart the consolidation process all over again, every time it is
retrieved. This process is formally termed reconsolidation. These data
have a number of scientists questioning the entire notion of stability
in human memory. If consolidation is not a sequential one-time
event but one that occurs repeatedly every time a memory trace is
reactivated, it means permanent storage exists in our brains only for
those memories we choose not to recall! Oh, good grief. Does this
mean that we can never be aware of something permanent in our
lives? Some scientists think this is so. And if it is true, the case I am
about to make for repetition in learning is ridiculously important.
retrieval
Like many radical university professors, our retrieval systems are
powerful enough to alter our conceptions of the past while offering
nothing substantial to replace them. Exactly how that happens is an
important but missing piece of our puzzle. Still, researchers have
organized the mechanisms of retrieval into two general models. One
passively imagines libraries. The other aggressively imagines crime
scenes.

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In the library model, memories are stored in our heads the same
way books are stored in a library. Retrieval begins with a command
to browse through the stacks and select a specific volume. Once
selected, the contents of the volume are brought into conscious
awareness, and the memory is retrieved. This tame process is
sometimes called reproductive retrieval.
The other model imagines our memories to be more like a
large collection of crime scenes, complete with their own Sherlock
Holmes. Retrieval begins by summoning the detective to a particular
crime scene, a scene which invariably consists of a fragmentary
memory. Upon arrival, Mr. Holmes examines the partial evidence
available. Based on inference and guesswork, the detective then
invents a reconstruction of what was actually stored. In this model,
retrieval is not the passive examination of a fully reproduced, vividly
detailed book. Rather, retrieval is an active investigative effort to re-
create the facts based on fragmented data.
Which is correct? The surprising answer is both. Ancient
philosophers and modern scientists agree that we have different
types of retrieval systems. Which one we use may depend upon the
type of information being sought, and how much time has passed
since the initial memory was formed. This unusual fact requires
some explanation.
mind the gap
At relatively early periods post-learning (say minutes to hours
to days), retrieval systems allow us to reproduce a fairly specific
and detailed account of a given memory. This might be likened to
the library model. But as time goes by, we switch to a style more
reminiscent of the Sherlock Holmes model. The reason is that the
passage of time inexorably leads to a weakening of events and facts
that were once clear and chock-full of specifics. In an attempt to
fill in missing gaps, the brain is forced to rely on partial fragments,
inferences, outright guesswork, and often (most disturbingly) other

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memories not related to the actual event. It is truly reconstructive
in nature, much like a detective with a slippery imagination. This
is all in the service of creating a coherent story, which, reality
notwithstanding, brains like to do. So, over time, the brain’s many
retrieval systems seem to undergo a gradual switch from specific and
detailed reproductions to this more general and abstracted recall.
Pretend you are a freshman in high school and know a
psychiatrist named Daniel Offer. Taking out a questionnaire, Dr.
Dan asks you to answer some questions that are really none of his
business: Was religion helpful to you growing up? Did you receive
physical punishment as discipline? Did your parents encourage you
to be active in sports? And so on. Now pretend it is 34 years later.
Dr. Dan tracks you down, gives you the same questionnaire, and
asks you to fill it out. Unbeknownst to you, he still has the answers
you gave in high school, and he is out to compare your answers.
How well do you do? In a word, horribly. In fact, the memories you
encoded as adolescents bear very little resemblance to the ones you
remember as adults, as Dr. Dan, who had the patience to actually do
this experiment, found out. Take the physical punishment question.
Though only a third of adults recalled any physical punishment, such
as spanking, Dr. Dan found that almost 90 percent of the adolescents
had answered the question in the affirmative. These data are only
some that demonstrate the powerful inaccuracy of the Sherlock
Holmes style of retrieval.
This idea that the brain might cheerily insert false information
to make a coherent story underscores its admirable desire to create
organization out of a bewildering and confusing world. The brain
constantly receives new inputs and needs to store some of them in
the same head already occupied by previous experiences. It makes
sense of its world by trying to connect new information to previously
encountered information, which means that new information
routinely resculpts previously existing representations and sends
the re-created whole back for new storage. What does this mean?

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Merely that present knowledge can bleed into past memories and
become intertwined with them as if they were encountered together.
Does that give you only an approximate view of reality? You bet it
does. This tendency, by the way, can drive the criminal-justice system
crazy.
repetition
Given this predilection for generalizing, is there any hope of
creating reliable long-term memories? As the Brain Rule cheerily
suggests, the answer is yes. Memory may not be fixed at the moment
of learning, but repetition, doled out in specifically timed intervals, is
the fixative. Given its potential relevance to business and education,
it is high time we talked about it.
Here’s a test that involves the phonological loop of working
memory. Gaze at the following list of characters for about 30 seconds,
then cover it up before you read the next paragraph.
3 $ 8 ? A % 9
Can you recall the characters in the list without looking at them?
Were you able to do this without internally rehearsing them? Don’t be
alarmed if you can’t. The typical human brain can hold about seven
pieces of information for less than 30 seconds! If something does not
happen in that short stretch of time, the information becomes lost. If
you want to extend the 30 seconds to, say, a few minutes, or even an
hour or two, you will need to consistently re-expose yourself to the
information. This type of repetition is sometimes called maintenance
rehearsal. We now know that maintenance rehearsal is mostly good
for keeping things in working memory—that is, for a short period of
time. We also know there is a better way to push information into
long-term memory. To describe it, I would like to relate the first time
I ever saw somebody die.
Actually, I saw eight people die. Son of a career Air Force official,

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I was very used to seeing military airplanes in the sky. But I looked
up one afternoon to see a cargo plane do something I had never seen
before or since. It was falling from the sky, locked in a dead man’s
spiral. It hit the ground maybe 500 feet from where I stood, and I felt
both the shock wave and the heat of the explosion.
There are two things I could have done with this information. I
could have kept it entirely to myself, or I could have told the world. I
chose the latter. After immediately rushing home to tell my parents, I
called some of my friends. We met for sodas and began talking about
what had just happened. The sounds of the engine cutting out. Our
surprise. Our fear. As horrible as the accident was, we talked about
it so much in the next week that the subject got tiresome. One of my
teachers actually forbade us from bringing it up during class time,
threatening to make T-shirts saying, “You’ve done enough talking.”
Why do I still remember the details of this story? T-shirt threat
notwithstanding, my eagerness to yap about the experience provided
the key ingredient. The gabfest after the accident forced a consistent
re-exposure to the basic facts, followed by a detailed elaboration of
our impressions. The phenomenon is called elaborative rehearsal,
and it’s the type of repetition shown to be most effective for the
most robust retrieval. A great deal of research shows that thinking
or talking about an event immediately after it has occurred enhances
memory for that event, even when accounting for differences in
type of memory. This tendency is of enormous importance to law-
enforcement professionals. It is one of the reasons why it is so critical
to have a witness recall information as soon as is humanely possible
after a crime.
Ebbinghaus showed the power of repetition in exhaustive detail
almost 100 years ago. He even created “forgetting curves,” which
showed that a great deal of memory loss occurs in the first hour or
two after initial exposure. He demonstrated that this loss could be
lessened by deliberate repetitions. This notion of timing in the midst
of re-exposure is so critical, I am going to explore it in three ways.

140. BRAIN RULES
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space out the input
Much like concrete, memory takes an almost ridiculous amount
of time to settle into its permanent form. And while it is busy
hardening, human memory is maddeningly subject to amendment.
This probably occurs because newly encoded information can
reshape and wear away previously existing traces. Such interference
is especially true when learning is supplied in consecutive,
uninterrupted glops, much like what happens in most boardrooms
and schoolrooms. The probability of confusion is increased when
content is delivered in unstoppable, unrepeated waves, poured into
students as if they were wooden forms.
But there is happy news. Such interference does not occur if
the information is delivered in deliberately spaced repetition cycles.
Indeed, repeated exposure to information in specifically timed
intervals provides the most powerful way to fix memory into the
brain. Why does this occur? When the electrical representations of
information to be learned are built up slowly over many repetitions,
the neural networks recruited for storage gradually remodel the
overall representation and do not interfere with networks previously
recruited to store similarly learned information. This idea suggests
that continuous repetition cycles create experiences capable of
adding to the knowledge base, rather than interfering with the
resident tenants.
There is an area of the brain that always becomes active when a
vivid memory is being retrieved. The area is within the left inferior
prefrontal cortex. The activity of this area, captured by an fMRI
(that’s “functional magnetic resonance imaging”) machine during
learning, predicts whether something that was stored is being
recalled in crystal-clear detail. This activity is so reliable that if
scientists want to know if you are retrieving something in a robust
manner, they don’t have to ask you. They can simply look in their
machine and see what your left inferior prefrontal cortex is doing.

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With this fact in mind, scientist Robert Wagner designed an
experiment in which two groups of students were required to
memorize a list of words. The first group was shown the words via
mass repetition, reminiscent of students cramming for an exam. The
second group was shown the words in spaced intervals over a longer
period of time, no cramming allowed. In terms of accurate retrieval,
the first group fared much worse than the second; activity in the
left inferior prefrontal cortex was greatly reduced. These results led
Harvard psychology professor Dan Schacter to say: “If you have only
one week to study for a final, and only 10 times when you can hit the
subject, it is better to space out the 10 repetitions during the week
than to squeeze them all together.”
Taken together, the relationship between repetition and
memory is clear. Deliberately re-expose yourself to the information
if you want to retrieve it later. Deliberately re-expose yourself to
the information more elaborately if you want the retrieval to be of
higher quality. Deliberately re-expose yourself to the information
more elaborately, and in fixed, spaced intervals, if you want the
retrieval to be the most vivid it can be. Learning occurs best when
new information is incorporated gradually into the memory store
rather than when it is jammed in all at once. So why don’t we use
such models in our classrooms and boardrooms? Partly it’s because
educators and business people don’t regularly read the Journal of
Neuroscience. And partly it’s because the people who do aren’t yet
sure which time intervals supply all the magic. Not that timing issues
aren’t a powerful research focus. In fact, we can divide consolidation
into two categories based on timing: fast and slow. To explain how
timing issues figure into memory formation, I want to stop for a
moment and tell you about how I met my wife.
sparking interest
I was dating somebody else when I first met Kari—and so was
she. But I did not forget Kari. She is a physically beautiful, talented,

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Emmy-nominated composer, and one of the nicest people I have
ever met. When we both became “available” six months later, I
immediately asked her out. We had a great time, and I began thinking
about her more and more. Turns out she was feeling the same. I asked
her out again, and soon we were seeing each other regularly. After
two months, it got so that every time we met, my heart would pound,
my stomach would flip-flop, and I’d get sweaty palms. Eventually I
didn’t even have to see her to raise my pulse. Just a picture would do,
or a whiff of her perfume, or … just music! Even a fleeting thought
was enough to send me into hours of rapture. I knew I was falling in
love.
What was happening to effect such change? With increased
exposure to this wonderful woman, I became increasingly sensitive to
her presence, needing increasingly smaller “input” cues (perfume, for
heavens sake?) to elicit increasingly stronger “output” responses. The
effect has been long-lasting, with a tenure of almost three decades.
Leaving the whys of the heart to poets and psychiatrists, the idea that
increasingly limited exposures can result in increasingly stronger
responses lies at the heart of how neurons learn things. Only it’s not
called romance; it’s called long-term potentiation.
To describe LTP, we need to leave the high-altitude world of
behavioral research and drop down to the more intimate world of
cellular and molecular research. Let’s suppose you and I are looking
at a laboratory Petri dish where two hippocampal neurons happily
reside in close synaptic association. I will call the presynaptic neuron
the “teacher” and the post-synaptic neuron the “student.” The goal
of the teacher neuron is to pass on information, electrical in nature,
to the student cell. Let’s give the teacher neuron some stimulus
that inspires the cell to crack off an electrical signal to its student.
For a short period of time, the student becomes stimulated and fires
excitedly in response. The synaptic interaction between the two is
said to be temporarily “strengthened.” This phenomenon is termed
early LTP.

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Unfortunately, the excitement lasts only for an hour or two. If the
student neuron does not get the same information from the teacher
within about 90 minutes, the student neuron’s level of excitement
will vanish. The cell will literally reset itself to zero and act as if
nothing happened, ready for any other signal that might come its
way.
Early LTP is at obvious cross-purposes with the goals of the
teacher neuron and, of course, with real teachers everywhere. How
does one get that initial excitement to become permanent? Is there
a way to transform a student’s short-lived response into a long-lived
one?
You bet there is: The information must be repeated after a period
of time has elapsed. If the signal is given only once by the cellular
teacher, the excitement will be experienced by the cellular student
only transiently. But if the information is repeatedly pulsed in
discretely timed intervals (the timing for cells in a dish is about 10
minutes between pulses, done a total of three times), the relationship
between the teacher neuron and the student neuron begins to
change. Much like my relationship with Kari after a few dates,
increasingly smaller and smaller inputs from the teacher are required
to elicit increasingly stronger and stronger outputs from the student.
This response is termed “late LTP.” Even in this tiny, isolated world of
two neurons, timed repetition is deeply involved in whether or not
learning will occur.
The interval required for synaptic consolidation is measured in
minutes and hours, which is why it is called fast consolidation. But
don’t let this small passage of time disabuse you of its importance.
Any manipulation—behavioral, pharmacological, or genetic—that
interferes with any part of this developing relationship will block
memory formation in total.
Such data provide rock solid evidence that repetition is critical
in learning—at least, if you are talking about two neurons in a dish.
How about between two people in a classroom? The comparatively

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simple world of the cell is very different from the complex world of
the brain. It is not unusual for a single neuron to have hundreds of
synaptic connections with other neurons.
This leads us to a type of consolidation measured in decidedly
longer terms, and to stronger end-use implications. It is sometimes
called “system consolidation,” sometimes “slow consolidation.” As we
shall see, slow is probably the better term.
a chatty marriage
Nuclear annihilation is a good way to illustrate the differences
between synaptic and system consolidation. On August 22, 1968, the
Cold War got hot. I was studying history in junior high at the time,
living with my Air Force-tethered family at an air base in central
Germany, unhappily near ground zero if the atomics were ever to fly
in the European theater.
If you could have visited my history class, you wouldn’t have
liked it. For all the wonderfully intense subject matter—Napoleonic
Wars!—the class was taught in a monotonic fashion by a French
national, a teacher who really didn’t want to be there. And it didn’t
help my concentration to be preoccupied with the events of the
previous day. August 21, 1968, was the morning when a combined
contingent of Soviet and Warsaw Pact armies invaded what used to
be Czechoslovakia. Our air base went on high alert, and my dad, a
member of the U.S. Air Force, had left the evening before. Ominously,
he had not yet come home.
The instructor pointed to a large and beautiful painting of the
Battle of Austerlitz on the wall, tediously discussing the early wars
of Napoleon. I suddenly heard her angry voice say, “Do I need to ask
zees twice?” Jolted out of my worried distraction, I turned around to
find her looming over my desk. She cleared her throat. “I said, ‘Who
were Napoleon’s enemies in zees battle?’ I suddenly realized she had
been talking to me, and I blurted out the first words that came to my
addled mind. “The Warsaw Pact armies! No? Wait! I mean the Soviet

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Union!” Fortunately, the teacher had a sense of humor and some
understanding about the day. As the class erupted with laughter, she
quickly thawed, tapped my shoulder, and walked back to her desk,
shaking her head. “Zee enemies were a coalition of Russian and
Austrian armies.” She paused. “And Napoleon cleaned their clocks.”
Many memory systems are involved in helping me to retrieve
this humiliating memory, now almost four decades old. I want to
use some of its semantic details to describe the timing properties of
system consolidation.
Like Austerlitz, our neurological tale involves several armies of
nerves. The first army is the cortex, that wafer-thin layer of nerves
that blankets a brain the way an atmosphere blankets a battlefield.
The second is a bit of a tongue twister, the medial temporal lobe. It
houses another familiar old soldier, the oft-mentioned hippocampus.
Crown jewel of the limbic system, the hippocampus helps shape the
long-term character of many types of memory. That other teacher-
student relationship we were discussing, the one made of neurons,
takes place in the hippocampus.
How the cortex and the medial temporal lobe are cabled together
tells the story of long-term memory formation. Neurons spring
from the cortex and snake their way over to the lobe, allowing the
hippocampus to listen in on what the cortex is receiving. Wires
also erupt from the lobe and wriggle their way back to the cortex,
returning the eavesdropping favor. This loop allows the hippocampus
to issue orders to previously stimulated cortical regions while
simultaneously gleaning information from them. It also allows us to
form memories, and it played a large role in my ability to recount this
story to you.
The end result of their association is the creation of long-term
memories. How they work to provide stable memories is not well
understood, even after three decades of research. We do know
something about the characteristics of their communication:
1) Sensory information comes into the hippocampus from

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the cortex, and memories form in the cortex by way of the reverse
connections.
2) Their electrical marriage starts out being amazingly chatty.
Long after the initial stimulus has exited, the hippocampus and the
relevant cortical neurons are still yapping about it. Even when I
went to bed that night, the hippocampus was busy feeding signals
about Austerlitz back to the cortex, replaying the memory over
and over again while I slept. This offline processing provides an
almost absurdly powerful reason to advocate for regular sleep. The
importance of sleep to learning is described in detail in Chapter 7.
3) While these regions are actively engaged, any memory they
mediate is labile and subject to amendment. But it doesn’t stay that
way.
4) After an elapsed period of time, the hippocampus will let go
of the cortex, effectively terminating the relationship. This will
leave only the cortex holding the memory of the event. But there’s
an important caveat. The hippocampus will file for cellular divorce
only if the cortical memory has first become fully consolidated–only
if the memory has changed from transient and amendable to durable
and fixed. The process is at the heart of system consolidation, and it
involves a complex reorganization of the brain regions supporting a
particular memory trace.
So how long does it take for a piece of information, once
recruited for long-term storage, to become completely stable?
Another way of asking the question is: How long does it take before
the hippocampus lets go of its cortical relationship? Hours? Days?
Months? The answer surprises nearly everybody who hears it for the
first time. The answer is: It can take years.
memories on the move
Remember H.M., the fellow whose hippocampus was surgically
removed, and along with it the ability to encode new information?
H.M. could meet you twice in two hours, with absolutely no

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recollection of the first meeting. This inability to encode information
for long-term storage is called anterograde amnesia. Turns out this
famous patient also had retrograde amnesia, a loss of memory of the
past. You could ask H.M. about an event that occurred three years
before his surgery. No memory. Seven years before his surgery. No
memory. If that’s all you knew about H.M, you might conclude that
his hippocampal loss created a complete memory meltdown. But
that’s where you’d be wrong. If you asked H.M. about the distant past,
say early childhood, he would display a perfectly normal recollection,
just as you and I might. He can remember his family, where he lived,
details of various events, and so on. This is a conversation with a
researcher who studied him for many years:
Researcher: Can you remember any particular event that was
special—like a holiday, Christmas, birthday, Easter?
(Now remember, this is a fellow who cannot ever remember
meeting this researcher before this interview, though the
researcher has worked with him for decades.)
H.M.: There I have an argument with myself about Christmas
time.
Researcher: What about Christmas?
H.M.: Well, ’cause my daddy was from the South, and he
didn’t celebrate down there like they do up here—in the
North. Like they don’t have the trees or anything like that.
And uh, but he came North even though he was born down
Louisiana. And I know the name of the town he was born in.
If H.M can recall certain details about his distant past, there
must be a point where memory loss began. Where was it? Close

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analysis revealed that his memory doesn’t start to sputter until you
get to about the 11th year before his surgery. If you were to graph
his memory, you would start out with a very high score and then, 11
years before his surgery, drop it to near zero, where it would remain
forever.
What does that mean? If the hippocampus were involved in all
memory abilities, its complete removal should destroy all memory
abilities—wipe the memory clean. But it doesn’t. The hippocampus
is relevant to memory formation for more than a decade after the
event was recruited for long-term storage. After that, the memory
somehow makes it to another region, one not affected by H.M.’s brain
losses, and as a result, H.M. can retrieve it. H.M., and patients like
him, tell us the hippocampus holds on to a newly formed memory
trace for years. Not days. Not months. Years. Even a decade or more.
System consolidation, that process of transforming a labile memory
into a durable one, can take years to complete. During that time, the
memory is not stable.
There are, of course, many questions to ask about this process.
Where does the memory go during those intervening years? Joseph
LeDoux has coined the term “nomadic memory” to illustrate
memory’s lengthy sojourn through the brain’s neural wilderness. But
that does not answer the question. Currently nobody knows where it
goes, or even if it goes. Another question: Why does the hippocampus
eventually throw in the towel with its cortical relationships, after
spending years nurturing them? Where is the final resting place of
the memory once it has fully consolidated? At least in response
to that last question, the answer is a bit clearer. The final resting
place for the memory is a region that will be very familiar to movie
buffs, especially if you like films such as The Wizard of Oz, The Time
Machine, and the original Planet of the Apes.
Planet of the Apes was released in 1968, the same year of the Soviet
invasion, and appropriately dealt with apocalyptic themes. The main
character, a spaceman played by Charleton Heston, had crash-landed

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onto a planet ruled by apes. Having escaped a gang of malevolent
simians at the end of the movie, the last frames show Heston walking
along a beach. Suddenly, he sees something off camera of such
significance that it makes him drop to his knees. He screams. “You
finally did it. God damn you all to hell!” and pounds his fists into the
surf, sobbing.
As the camera pulls back from Heston, you see the outline of
a vaguely familiar sculpture. Eventually the Statue of Liberty is
revealed, half buried in the sand, and then it hits you why Heston is
screaming. After this long cinematic journey, he wasn’t adventuring
on foreign soil. Heston never left Earth. His ending place was the
same as his starting place, and the only difference was the timeline.
His ship had “crashed” at a point in the far future, a post-apocalyptic
Earth now ruled by apes. The first time I encountered data
concerning the final resting place of a fully consolidated memory, I
immediately thought of this movie.
You recall that the hippocampus is wired to receive information
from the cortex as well as return information to it. Declarative
memories appear to be terminally stored in the same cortical systems
involved in the initial processing of the stimulus. In other words,
the final resting place is also the region that served as the initial
starting place. The only separation is time, not location. These data
have a great deal to say not only about storage but also about recall.
Retrieval for a fully mature memory trace 10 years later may simply
be an attempt to reconstruct the initial moments of learning, when
the memory was only a few milliseconds old! So, the current model
looks something like this:
1) Long-term memories occur from accumulations of synaptic
changes in the cortex as a result of multiple reinstatements of the
memory.
2) These reinstatements are directed by the hippocampus,
perhaps for years.
3) Eventually the memory becomes independent of the medial

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temporal lobe, and this newer, more stable memory trace is
permanently stored in the cortex.
4) Retrieval mechanisms may reconstruct the original pattern of
neurons initially recruited during the first moments of learning.
forgetting
Solomon Shereshevskii, a Russian journalist born in 1886,
seemed to have a virtually unlimited memory capacity, both for
storage and for retrieval. Scientists would give him a list of things to
memorize, usually combinations of numbers and letters, and then
test his recall. As long as he was allowed 3 or 4 seconds to “visualize”
(his words) each item, he could repeat the lists back perfectly, even
if the lists had more than 70 elements. He could also repeat the list
backward.
In one experiment, a researcher exposed Shereshevskii to a
complex formula of letters and numbers containing about 30 items.
After a single retrieval test (which Shereshevskii accomplished
flawlessly), the researcher put the list in a box, and waited 15 years.
The scientist then took out the list, found Shereshevskii, and asked
him to repeat the formula. Without hesitation, he reproduced the
list on the spot, again without error. Shereshevskii’s memory of
everything he encountered was so clear, so detailed, so unending, he
lost the ability to organize it into meaningful patterns. Like living
in a permanent snowstorm, he saw much of his life as blinding
flakes of unrelated sensory information, He couldn’t see the “big
picture,” meaning he couldn’t focus on commonalities between
related experiences and discover larger, repeating patterns. Poems,
carrying their typical heavy load of metaphor and simile, were
incomprehensible to him. In fact, he probably could not make sense
of the sentence you just read. Shereshevskii couldn’t forget, and it
affected the way he functioned.
The last step in declarative processing is forgetting. The reason
forgetting plays a vital role in our ability to function is deceptively

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simple. Forgetting allows us to prioritize events. Those events that
are irrelevant to our survival will take up wasteful cognitive space if
we assign them the same priority as events critical to our survival. So
we don’t. We insult them by making them less stable. We forget them.
There appear to be many types of forgetting, categories
cleverly enumerated by Dan Schacter, the father of research on the
phenomenon, in his book The Seven Sins of Memory. Tip-of-the-
tongue issues, absent-mindedness, blocking habits, misattribution,
biases, suggestibility—the list reads like a cognitive Chamber of
Horrors for students and business professionals alike. Regardless
of the type of forgetting, they all have one thing in common. They
allow us to drop pieces of information in favor of others. In so doing,
forgetting helped us to conquer the Earth.
ideas
How can we use all of this information to conquer the classroom?
The boardroom? Exploring the timing of information re-exposure
is one obvious arena where researchers and practitioners might do
productive work together. For example, we have no idea what this
means for marketing. How often must you repeat the message before
people buy a product? What determines whether they still remember
it six months later, or a year later?
Minutes and hours
The day of a typical high-school student is segmented into five
or six 50-minute periods, consisting of unrepeated (and unrelenting)
streams of information. Using as a framework the timing
requirements suggested by working memory, how would you change
this five-period fire hose? What you’d come up with might be the
strangest classroom experience in the world. Here’s my fantasy:
In the school of the future, lessons are divided into 25-minute
modules, cyclically repeated throughout the day. Subject A is taught
for 25 minutes, constituting the first exposure. Ninety minutes later,

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the 25-minute content of Subject A is repeated, and then a third time.
All classes are segmented and interleaved in such a fashion. Because
these repetition schedules slow down the amount of information
capable of being addressed per unit of time, the school year is
extended into the summer.
Days and weeks
We know from Robert Wagner that multiple reinstatements
provide demonstrable benefit over periods of days and even weeks.
In the future school, every third or fourth day would be reserved
for reviewing the facts delivered in the previous 72 to 96 hours.
During these “review holidays,” previous information would be
presented in compressed fashion. Students would have a chance to
inspect the notes they took during the initial exposures, comparing
them with what the teacher was saying in the review. This would
result in a greater elaboration of the information, and it would help
the teachers deliver accurate information. A formalized exercise in
error-checking soon would become a regular and positive part of
both the teacher and student learning experiences.
It is quite possible that such models would eradicate the need for
homework. At its best, homework served only to force the student to
repeat content. If that repetition were supplied during the course of
the day, there might be little need for further re-exposure. This isn’t
because homework isn’t important as a concept. In the future school,
it may simply be unnecessary.
Could models like these actually work? Deliberately spaced
repetitions have not been tested rigorously in the real world, so there
are lots of questions. Do you really need three separate repetitions
per subject per day to accrue a positive outcome? Do all subjects
need such repetition? Might such interleaved vigor hurt learning,
with constant repetitions beginning to interfere with one another as
the day wore on? Do you really need review holidays, and if so, do
you need them every three to four days? We don’t know.

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Years and years
Today, students are expected to know certain things by certain
grades. Curiously absent from this model is how durable that
learning remains after the student completes the grade. Given that
system consolidation can take years, might the idea of grade-level
expectations need amending? Perhaps learning in the long view
should be thought of the same way one thinks of immune booster
shots, with critical pieces of information being repeated on a yearly
or semi-yearly basis.
In my fantasy class, this is exactly what happens. Repetitions
begin with a consistent and rigorous review of multiplication tables,
fractions, and decimals. First learned in the third grade, six-month
and yearly review sessions on these basic facts occur through sixth
grade. As mathematical competencies increase in sophistication,
the review content is changed to reflect greater understanding. But
the cycles are still in place. In my fantasy, these consistent repetition
disciplines, stretched out over long periods of time, create enormous
benefits for every academic subject, especially foreign languages.
You’ve probably heard that many corporations, especially in
technical fields, are disappointed by the quality of the American
undergraduates they hire. They have to spend money retraining many
of their newest employees in certain basic skills that they often think
should have been covered in college. One of my business fantasies
would partner engineering firms with colleges of engineering. It
involves shoring up this deficit by instituting post-graduate repetition
experiences. These reinstatement exercises would be instituted
the week after graduation and continue through the first year of
employment. The goal? To review every important technical subject
relevant to the employee’s new job. Research would establish not only
the choice of topics to be reviewed but also the optimal spacing of
the repetition.
My fantasy shares the teaching load between firm members and

154. BRAIN RULES
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the academic community, extending the idea of a bachelor’s degree
into the workplace. This hybridization aligns business professionals
with researchers, ensuring that companies have exposure to the
latest advances in their fields (and informing researchers on the
latest practical day-to-day issues business professionals face). In my
fantasy, the program becomes so popular that the more experienced
engineers also begin attending these refresher courses, inadvertently
rubbing shoulders with younger generations. The old guard is
surprised by how much they have forgotten, and how much the
review and cross-hybridization, both with research professionals and
younger students, aid their own job performance.
I wish I could tell you this all would work, but instead all I
can say is that memory is not fixed at the moment of learning, and
repetition provides the fixative.

155. 6. LONG-TERM MEMORY
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Summary
Rule #6
Remember to repeat.
Most memories disappear within minutes, but those
•
•
that survive the fragile period strengthen with time.
Long-term memories are formed in a two-way
•
•
conversation between the hippocampus and the cortex,
until the hippocampus breaks the connection and the
memory is fixed in the cortex—which can take years.
Our brains give us only an approximate view of reality,
•
•
because they mix new knowledge with past memories and
store them together as one.
The way to make long-term memory more reliable is
•
•
to incorporate new information gradually and repeat it in
timed intervals.
Get more at www.brainrules.net

157. sleep
Rule #7
Sleep well, think well.

159. it’s not the most comfortable way to earn an entry
in the Guinness Book of World Records, obtain an
A on a high-school science-fair project, and meet a
world-famous scientist. In 1965, 17-year-old Randy Gardner decided
that his science-fair project would involve not sleeping for 11 straight
days and observing what happened. To the astonishment of just about
everyone, he accomplished the feat, setting a world record that year
for sleep loss. The project attracted the attention of scientist William
Dement, who was given permission to study what happened to the
teenager’s mind during the week and a half he was awake.
What happened to Randy’s mind was extraordinary. To put
it charitably, it started to malfunction. In short order, he became
irritable, forgetful, nauseous, and, to no one’s surprise, unbelievably
tired. Five days into his experiment, Randy began to suffer from what
could pass for Alzheimer’s disease. He was actively hallucinating,
severely disoriented, and paranoid. He thought a local radio host
was out to get him because of his changes in memory. In the last four

160. BRAIN RULES
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days of his experiment, he lost motor function, his fingers trembling
and his speech slurred. Curiously, on the final day, he still was able to
beat Dement at pinball, doing so 100 consecutive times.
Some unfortunate souls don’t have the luxury of experimenting.
They become suddenly—and permanently—incapable of ever
going to sleep again. Fatal Familial Insomnia is one of the rarest
human genetic disorders that exists, affecting only about 20
families worldwide. That rarity is a blessing, because the disease
follows a course straight through mental-health hell. In middle to
late adulthood, the person begins to experience fevers, tremors,
and profuse sweating. As the insomnia becomes permanent, these
symptoms are accompanied by increasingly uncontrollable muscular
jerks and tics. The person soon experiences crushing feelings of
depression and anxiety. He or she becomes psychotic. Finally,
mercifully, the patient slips into a coma and dies.
So we know bad things happen when we don’t get any sleep. But,
considering that sleep occupies a walloping one-third of our time on
the planet, it is incredible to contemplate that we still don’t know
why we need to sleep. Not that there haven’t been clues. One strong
hint came about 10 years ago, from a group of researchers who left
a bunch of wires stuck inside a rat’s brain. The rat had just learned
to negotiate a maze when it decided to take a nap. The recording
device was still attached to those wires, and it was still on. But to
understand how this relates to the purpose of sleep, let’s look at what
the brain is doing while we sleep.
you call this rest?
If you ever get a chance to listen in on a living brain while it is
slumbering, you’ll have to get over your disbelief. The brain does
not appear to be asleep at all. Rather, it is almost unbelievably active
during “rest,” with legions of neurons crackling electrical commands
to one another in constantly shifting patterns—displaying greater
rhythmical activity during sleep, actually, than when it is wide awake.

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The only time you can observe a real resting period for the brain
(where the amount of energy consumed is less than during a similar
awake period) is in the deepest parts of what is called non-REM
sleep. But that takes up only about 20 percent of the total sleep cycle,
which is why researchers early on began to disabuse themselves of
the notion that the reason we rest is so that we can rest. When the
brain is asleep, the brain is not resting at all.
Even so, most people report that sleep is powerfully restorative,
and they point to the fact that if they don’t get enough sleep, they
don’t think as well. That is measurably true, as we shall see shortly.
And so we find ourselves in a quandary: Given the amount of
energy the brain is using, it seems impossible that you could receive
anything approaching mental rest and restoration during sleep.
Even if the brain doesn’t behave itself bioenergetically, other parts
of the body do rest during sleep, in something like a human version
of micro-hibernation. That introduces a second puzzle: Sleep makes
us exquisitely vulnerable to predators. Indeed, deliberately going off
to dreamland unprotected in the middle of a bunch of hostile hunters
(such as leopards, our evolutionary roommates in eastern Africa)
seems like a behavior dreamed up by our worst enemies. There must
be something terribly important we need to accomplish during sleep
if we are willing to take such risks in order to get it. Exactly what is it
that is so darned important?
The scientist who studied sleepless Randy Gardner made a
substantial early contribution to answering such questions. Often
called the father of sleep research, Dement is a white-haired man
with a broad smile who at this writing is in his late 70s. He says pithy
things about our slumbering habits, such as “Dreaming permits each
and every one of us to be quietly and safely insane every night of our
lives.”
Dement studied many aspects of the human sleep cycle. What
he began to uncover was this: “Sleeping” brains, like soldiers on a
battlefield, are actually locked in vicious, biological combat. The

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conflict involves a pitched battle between two powerful and opposing
drives, each made of legions of brain cells and biochemicals with
very different agendas. Though localized in the head, the theater of
operations for these armies engulfs every corner of the body. This
fight is sometimes referred to as the “opponent process” model.
As Dement began to define these two opposing drives, he noticed
some strange things about the war they were waging. First, these
forces are not engaged just during the night, while we sleep, but also
during the day, while we are awake. Second, they are doomed to a
combat schedule in which each army sequentially wins one battle,
then promptly loses the next battle, then quickly wins the next and so
on, cycling through this win/loss column every day and every night.
The third strange thing is that no one army ever claims final victory
in this war. This incessant engagement results in the cyclical waking
and sleeping experiences all humans encounter every day (and night)
of our lives.
Dement was not working in isolation. His mentor, a gifted
researcher named Nathaniel Kleitman, gave him many of his initial
insights. If Dement can be considered the father of sleep research,
Kleitman certainly could qualify as its grandfather. An intense
Russian man with bushy eyebrows, Nathaniel Kleitman may be best
noted for his willingness to experiment not only on himself but
also on his children. When it appeared that a colleague of his had
discovered Rapid Eye Movement (REM) sleep, Kleitman promptly
volunteered his daughter for experimentation, and she just as
promptly confirmed the finding. But one of the most interesting
experiments of Kleitman’s long career occurred in 1938, when he
persuaded a colleague to join him 150 feet underground in Mammoth
Cave in Kentucky for an entire month.
Free of sunlight and daily schedules, Kleitman could ask
whether the routines of wakefulness and sleep cycled themselves
automatically through the human body. His observations were mixed,
but the experiment provided the first real hint that such an automatic

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device did exist in our bodies. Indeed, we now know that the body
possesses a series of internal clocks, all controlled by discrete regions
in the brain, providing a regular rhythmic schedule to our waking
and sleeping experiences. This is surprisingly similar to the buzzing
of a wristwatch’s internal quartz crystal. An area of the brain called
the suprachiasmatic nucleus, part of that hypothalamus we discussed
earlier, appears to contain just such a timing device. Of course, we
have not been characterizing these pulsing rhythms as a benign
wristwatch. We have been characterizing them as a violent war. One
of Kleitman’s and Dement’s greatest contributions was to show that
this nearly automatic rhythm occurs as a result of the continuous
conflict between two opposing forces.
With the idea that such forces are under internal control, we can
explore them in greater detail, beginning with a description of their
names. One army is composed of neurons, hormones, and various
other chemicals that do everything in their power to keep you awake.
This army is called the circadian arousal system (often referred to
simply as “process C”). If this army had its way, it would make you
stay up all the time. Fortunately, it is opposed by an equally powerful
army, also made of brain cells, hormones, and various chemicals.
These combatants do everything in their power to put you to sleep.
They are termed the homeostatic sleep drive ( “process S”). If this
army had its way, you would go to sleep and never wake up.
It is a strange, even paradoxical, war. The longer one army
controls the field, for example, the more likely it is to lose the battle.
It’s almost as if each army becomes exhausted from having its way
and eventually waves a temporary white flag. Indeed, the longer you
are awake (the victorious process C doing victory laps around your
head), the greater the probability becomes that the circadian arousal
system will eventually cede the field to its opponent. You then go to
sleep. For most people, this act of capitulation comes after about 16
hours of active consciousness. This will occur even if you are living
in a cave.

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Conversely, the longer you are asleep (the triumphant process
S now doing the heady victory laps), the greater the probability
becomes that the homeostatic sleep drive will similarly cede the field
to its opponent, which is, of course, the drive to keep you awake. The
result of this surrender is that you wake up. For most people, the
length of time prior to capitulation is about half of its opponent’s,
about eight hours of blissful sleep. And this also will occur even if
you are living in a cave.
Except for the unfortunate members of 20 or so families
worldwide, Kleitman, Dement, and a host of other researchers were
able to show that such dynamic tension is a normal—even critical—
part of our daily lives. In fact, the circadian arousal system and the
homeostatic sleep drive are locked in a daily warfare of victory and
surrender so predictable, you can actually graph it. Stated formally,
process S maintains the duration and intensity of sleep, while process
C determines the tendency and timing of the need to go to sleep.
Now, this war between the two armies does not go unsupervised.
Internal and external forces help regulate the conflict, defining for
us both the amount of sleep we need and the amount of sleep we get.
We will focus on two of the internal forces, chronotype and the nap
zone. To understand how these work, we must leave the intricacies
of battle for a moment and explore instead the life of newspaper
cartoonists and advice columnists. Oh, and we will also talk about
birds.
lark or owl?
The late advice columnist Ann Landers would vehemently
declare, “No one’s going to call me until I’m ready!” and then take
her phone off the hook between 1 and 10 a.m. Why? This was the
time she normally went to sleep. The cartoonist Scott Adams, creator
of the comic strip Dilbert, never would think of starting his day at 10
a.m. “I’m quite tuned into my rhythms,” he has said. “I never try to
do any creating past noon. … I do the strip from 6 to 7 a.m.” Here

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we have two creative and well-accomplished professionals, one who
starts working just as the other’s workday is finished.
About 1 in 10 of us is like Dilbert’s Adams. The scientific literature
calls such people larks (more palatable than the proper term, “early
chronotype”). In general, larks report being most alert around noon
and feel most productive at work a few hours before they eat lunch.
They don’t need an alarm clock, because they invariably get up
before the alarm rings—often before 6 a.m. Larks cheerfully report
their favorite mealtime as breakfast and generally consume much
less coffee than non-larks. Getting increasingly drowsy in the early
evening, most larks go to bed (or want to go to bed) around 9 p.m.
Larks are the mortal enemy of the 2 in 10 humans who lie at the
other extreme of the sleep spectrum: “late chronotypes,” or owls. In
general, owls report being most alert around 6 p.m., experiencing
their most productive work times in the late evening. They rarely
want to go to bed before 3 a.m. Owls invariably need an alarm
clock to get them up in the morning, with extreme owls requiring
multiple alarms to ensure arousal. Indeed, if owls had their druthers,
most would not wake up much before 10 a.m. Not surprisingly, late
chronotypes report their favorite mealtime as dinner, and they would
drink gallons of coffee all day long to prop themselves up at work if
given the opportunity. If it sounds to you as though owls do not sleep
as well as larks in our society, you are right on the money. Indeed,
late chronotypes usually accumulate a massive “sleep debt” as they go
through life.
The behaviors of larks and owls are very specific. Researchers
think these patterns are detectable in early childhood and burned
into the genetic complexities of the brain that govern our sleep/wake
cycle. At least one study shows that if Mom or Dad is a lark, half of
their kids will be, too. Larks and owls cover only about 30 percent
of the population. The rest of us are called hummingbirds. True to
the idea of a continuum, some hummingbirds are more owlish, some
are more larkish, and some are in between. To my knowledge, no

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birdish moniker has ever been applied to those people who seem to
need only four or five hours of sleep. They instead are referred to as
suffering from “healthy insomnia.”
So how much sleep does a person need? Given all of our recent
understanding about how and when we sleep, you might expect that
scientists would come up with the answer fairly quickly. Indeed, they
have. The answer is: We don’t know. You did not read that wrong.
After all of these centuries of experience with sleep, we still don’t
know how much of the stuff people actually need. Generalizations
don’t work: When you dig into the data on humans, what you find
is not remarkable uniformity but remarkable individuality. To make
matters worse, sleep schedules are unbelievably dynamic. They
change with age. They change with gender. They change depending
upon whether or not you are pregnant, and whether or not you are
going through puberty. There are so many variables one must take
into account that it almost feels as though you’ve asked the wrong
question. So let’s invert the query. How much sleep don’t you need?
In other words, what are the numbers that disrupt normal function?
That turns out to be an important question, because it is possible to
become dysfunctional with too much sleep or not enough. Whatever
amount of sleep is right for you, when robbed of that (in either
direction), bad things really do happen to your brain.
napping in the free world
Given that sleep rhythms fight their battles 24 hours a day,
researchers have studied the skirmishes occurring not only in the
night but also in the day. One area of interest is the persistent need
to take a nap, and to do so at very specific times of the day.
It must have taken some getting used to, if you were a staffer
in the socially conservative early 1960s. Lyndon Baines Johnson,
36th
president of the United States and leader of the free world,
routinely closed the door to his office in the midafternoon and put
on his pajamas. He then proceeded to take a 30-minute nap. Rising

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refreshed, he would tell aides that such a nap gave him the stamina to
work the long hours required of the U.S. commander-in-chief during
the Cold War. Such presidential behavior might seem downright
weird. But if you ask sleep researchers like William Dement, his
response might surprise you: It was LBJ who was acting normally; the
rest of us, who refuse to bring our pajamas to work, are the abnormal
ones. And Dement has a fair amount of data to back him up.
LBJ was responding to something experienced by nearly everyone
on the planet. It goes by many names—the midday yawn, the post-
lunch dip, the afternoon “sleepies.” We’ll call it the nap zone, a period
of time in the midafternoon when we experience transient sleepiness.
It can be nearly impossible to get anything done during this time,
and if you attempt to push through, which is what most of us do, you
can spend much of your afternoon fighting a gnawing tiredness. It’s
a fight because the brain really wants to take a nap and doesn’t care
what its owner is doing. The concept of “siesta,” institutionalized in
many other cultures, may have come as an explicit reaction to the
nap zone.
At first, scientists didn’t believe the nap zone existed except as an
artifact of sleep deprivation. That has changed. We now know that
some people feel it more intensely than others. We know it is not
related to a big lunch (although a big lunch, especially one loaded
with carbs, can greatly increase its intensity). It appears, rather, to be
a part of our evolutionary history. Some scientists think that a long
sleep at night and a short nap during the midday represent human
sleep behavior at its most natural.
When you chart the process S curve and process C curve, you can
see that they flat-line in the same place—in the afternoon. Remember
that these curves are plotting the progress of a war between two
opposed groups of cells and biochemicals. The battle clearly has
reached a climactic stalemate. An equal tension now exists between
the two drives, which extracts a great deal of energy to maintain.
Some researchers, though not all, think this equanimity in tension

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drives the nap zone. Regardless, the nap zone matters, because our
brains don’t work as well during it. If you are a public speaker, you
already know it is darn near fatal to give a talk in the midafternoon.
The nap zone also is literally fatal: More traffic accidents occur
during it than at any other time of the day.
On the flip side, one NASA study showed that a 26-minute nap
improved a pilot’s performance by more than 34 percent. Another
study showed that a 45-minute nap produced a similar boost in
cognitive performance, lasting more than six hours. Still other
researchers demonstrated that a 30-minute nap taken prior to staying
up all night can prevent a significant loss of performance during that
night.
If that’s what a nap can do, imagine the benefits of a full night’s
sleep. Let’s look at what can happen when we ignore these internal
forces, and when we embrace them.
go ahead, sleep on it
If central casting ever called you to suggest a character in history
representing the archetypal brilliant-but-mad-looking scientist,
Dimitri Ivanovich Mendeleyev might be in your top five list. Hairy
and opinionated, Mendeleyev possessed the lurking countenance
of a Rasputin, the haunting eyes of Peter the Great, and the moral
flexibility of both. He once threatened to commit suicide if a young
lady didn’t marry him. She consented, which was quite illegal,
because, unbeknownst to the poor girl, Mendeleyev was already
married. This trespass kept him out of the Russian Academy of
Sciences for a while, which in hindsight may have been a bit rash,
as Mendeleyev single-handedly systematized the entire science of
chemistry.
His Periodic Table of the Elements—a way of organizing every
atom that had so far been discovered—was so prescient, it allowed
room for all the elements yet to be found and even predicted some of
their properties. But what’s most extraordinary is this: Mendeleyev

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says he first came up with the idea in his sleep. Contemplating
the nature of the universe while playing solitaire one evening, he
nodded off. When he awoke, he knew how all of the atoms in the
universe were organized, and he promptly created his famous table.
Interestingly, he organized the atoms in repeating groups of seven.
Mendeleyev is hardly the only scientist who has reported feelings
of inspiration after having slept, of course. Is there something to
the notion of “Let’s sleep on it”? What’s the relationship between
ordinary sleep and extraordinary learning?
Mountains of data demonstrate that a healthy sleep can
indeed boost learning significantly, in certain types of tasks. These
results generate a great deal of interest among sleep scientists and,
unsurprisingly, no small amount of controversy. How should we
define learning, they debate; exactly what is improvement? But there
are many examples of the phenomenon. One study stands out in
particular.
Students were given a series of math problems and prepped with
a method to solve them. The students weren’t told there was also an
easier, “shortcut” way to solve the problems, potentially discoverable
while doing the exercise. The question was: Is there any way to
jumpstart, even speed up, their insights? Can you get them to put this
other method on their radar screens? The answer was yes, if you allow
them to sleep on it. If you let 12 hours pass after the initial training and
ask the students to do more problems, about 20 percent will have
discovered the shortcut. But, if in that 12 hours you also allow eight
or so hours of regular sleep, that figure triples to about 60 percent.
No matter how many times the experiment is run, the sleep group
consistently outperforms the non-sleep group about 3 to 1.
Sleep has been shown to enhance tasks that involve visual texture
discrimination, motor adaptations, and motor sequencing. The type
of learning that appears to be most sensitive to sleep improvement is
that which involves learning a procedure. Simply disrupt the night’s
sleep at specific stages and retest in the morning, and you eliminate

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any overnight learning improvement. Clearly, for specific types of
intellectual skill, sleep can be a great friend to learning.
sleep loss = brain drain
It won’t surprise you, then, that lack of sleep hurts learning.
In fact, a highly successful student can be set up for a precipitous
academic fall, just by adjusting the number of hours she sleeps.
Take an A student used to scoring in the top 10 percent of virtually
anything she does. One study showed that if she gets just under
seven hours of sleep on weekdays, and about 40 minutes more on
weekends, she will begin to score in the bottom 9 percent of non-
sleep-deprived individuals. Cumulative losses during the week add
up to cumulative deficits during the weekend—and, if not paid for,
that sleep debt will be carried into the next week.
Another study followed soldiers responsible for operating
complex military hardware. One night’s loss of sleep resulted in about
a 30 percent loss in overall cognitive skill, with a subsequent drop in
performance. Bump that to two nights’ loss, and the figure becomes
60 percent. Other studies extended these findings. When sleep
was restricted to six hours or less per night for just five nights, for
example, cognitive performance matched that of a person suffering
from 48 hours of continual sleep deprivation.
More recent research has begun to shed light on other functions
that do not at first blush seem associated with sleep. When people
become sleep-deprived, for example, their ability to utilize the
food they are consuming falls by about one-third. The ability to
make insulin and to extract energy from the brain’s favorite dessert,
glucose, begins to fail miserably. At the same time, you find a marked
need to have more of it, because the body’s stress hormone levels
begin to rise in an increasingly deregulated fashion. If you keep up
the behavior, you appear to accelerate parts of the aging process.
For example, if healthy 30-year-olds are sleep-deprived for six days
(averaging, in this study, about four hours of sleep per night), parts of

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their body chemistry soon revert to that of a 60-year-old. And if they
are allowed to recover, it will take them almost a week to get back to
their 30-year-old systems.
The bottom line is that sleep loss means mind loss. Sleep loss
cripples thinking, in just about every way you can measure thinking.
Sleep loss hurts attention, executive function, immediate memory,
working memory, mood, quantitative skills, logical reasoning ability,
general math knowledge. Eventually, sleep loss affects manual
dexterity, including fine motor control (except, perhaps, for pinball)
and even gross motor movements, such as the ability to walk on a
treadmill.
When you look at all of the data combined, a consistency
emerges: Sleep is rather intimately involved in learning. It is
observable with large amounts of sleep; it is observable with small
amounts of sleep; it is observable all the time. Of course, explaining
exactly how sleep improves performance has not been as easy as
demonstrating the fact that it improves performance. Given the
importance of the issue to the Brain Rule, let’s try anyway.
Consider the following true story of a successfully married,
incredibly detail-oriented accountant. Even though dead asleep, he
regularly gives financial reports to his wife all night long. Many of
these reports come from the day’s activities. (Incidentally, if his wife
wakes him up—which is often, because his financial broadcasts are
loud—the accountant becomes amorous and wants to have sex.) Are
we all organizing our previous experiences while we sleep? Could
this not only explain all of the other data we have been discussing,
but also finally give us a reason why we sleep?
To answer these questions, we must return to our story of
the hapless rat who, 10 years ago, was unfortunate to have fallen
asleep with a bunch of wires stuck inside his brain. The “wires” are
electrodes placed near individual neurons. Hook these electrodes up
to a recording device, and you can eavesdrop on the brain while it
is talking to itself, something like a CIA phone tap, listening to the

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individual chatter of neurons as they process information. Even in a
tiny rat’s brain, it is not unusual these days to listen in on up to 500
neurons at once. So what are they all saying? If you listen in while
the rat is acquiring new information, like learning to navigate a
maze, you soon will detect something extraordinary. A very discrete
“maze-specific” pattern of electrical stimulation begins to emerge.
Working something like the old Morse code, a series of neurons
begin to crackle in a specifically timed sequence during the learning.
Afterward, the rat will always fire off that pattern whenever it travels
through the maze. It appears to be an electrical representation of the
rat’s new maze-navigating thought patterns (at least, as many as 500
electrodes can detect).
When the rat goes to sleep, it begins to replay the maze-pattern
sequence. The animal’s brain replays what it learned while it
slumbers, reminiscent of our accountant. Always executing the
pattern in a specific stage of sleep, the rat repeats it over and over
again—and much faster than during the day. The rate is so furious,
the sequence is replayed thousands of times. If a nasty graduate
student decides to wake up the rat during this stage, called slow-
wave sleep, something equally extraordinary is observed. The rat
has trouble remembering the maze the next day. Quite literally, the
rat seems to be consolidating the day’s learning the night after that
learning occurred, and an interruption of that sleep disrupts the
learning cycle.
This naturally caused researchers to ask whether the same was
true for humans. The answer? Not only do we do such processing,
but we do it in a far more complex fashion. Like the rat, humans
appear to replay certain daily learning experiences at night, during
the slow-wave phase. But unlike the rat, more emotionally charged
memories appear to replay at a different stage in the sleep cycle.
These findings represent a bombshell of an idea: Some kind of
offline processing is occurring at night. Is it possible that the reason
we need to sleep is simply to shut off the exterior world for a while,

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allowing us to divert more attentional resources to our cognitive
interiors? Is it possible that the reason we need to sleep is so that we
can learn?
It sounds compelling, but of course the real world of research
is much messier. Many findings appear to complicate, if not fully
contradict, the idea of offline processing. For example, brain-
damaged individuals who lack the ability to sleep in the slow-wave
phase nonetheless have normal, even improved, memory. So do
individuals whose REM sleep is suppressed by antidepressant
medications. Exactly how to reconcile these data with the previous
findings is a subject of intense scientific debate. What’s always
needed is more research—but not just at the lab bench.
ideas
What if businesses and schools took the sleep needs of their
employees and students seriously? What would a modern office
building look like? What would a school look like? These are not idle
questions. The effects of sleep deprivation are thought to cost U.S.
businesses more than $100 billion a year. I have a few ideas ripe for
real-world research.
Match chronotypes
A number of behavioral tests can discriminate larks from owls
from hummingbirds fairly easily. And given advances in genetic
research, you may in the future need only a blood test to characterize
your process C/process S graphs. The bottom line is, we can
determine the hours when a person is likely to experience his or her
major productivity peaks.
Here’s an obvious idea: What if we began to match chronotypes
to work schedules? Twenty percent of the workforce is already at
sub-optimal productivity in the current 9-to-5 model. What if we
created several work schedules, based on the chronotypes of the
employees? We might gain more productivity and a greater quality

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of life for those unfortunate employees who otherwise are doomed to
carry a permanent sleep debt. We might get more productive use out
of our buildings if they remained open instead of lying dormant half
the night. A business of the future will need to become involved in
some aspect of its employees’ sleep schedules.
We could do the same in education. Teachers are just as likely to
be late chronotypes as their students. Why not put them together?
Would you increase the competencies of the teacher? The students?
Free of the nagging consequences of their sleep debts, their
educational experiences might become more robust simply because
each was more fully capable of mobilizing his God-given IQ.
Variable schedules also would take advantage of the fact that
sleep needs change throughout a person’s life span. For example,
data suggest that students temporarily shift to more of an owlish
chronotype as they transit through their teenage years. This has led
some school districts to start their high-school classes after 9 a.m.
This may make some sense. Sleep hormones (such as the protein
melatonin) are at their maximum levels in the teenage brain. The
natural tendency of these kids is to sleep more, especially in the
morning. As we age, we tend to get less sleep, and some evidence
suggests we need less sleep, too. An employee who starts out with her
greatest productivity in one schedule may, as the years go by, keep a
similar high level of output simply by switching to a new schedule.
Promote naps
To embrace the midday nap zone, engineers at MetroNaps have
created a nap-on-the-go device called a Sleep Pod. “It looks like a
sperm that got electrocuted!” exclaimed one person upon seeing
the device for the first time. Actually, the pods are portable glorified
recliners that can fit in an office—complete with light-canceling
visors, noise-canceling earphones, heat-canceling circulation coils,
and—at more than $14,000 each—budget-canceling prices. The
company, based in New York, has pods in four countries and is busy

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expanding its business. Others are bringing naps into the workplace,
too. Hotels with stacked-bed “nap salons” have sprung up all over
Japan. A Boston-based researcher named William Anthony is trying
to create National Napping Day, a day set aside so that everybody can
take a nap. He finds that 70 percent of Americans who admit to being
workplace nappers still have to take their naps in secret. The favored
clandestine venue? In the back seat of the employee’s car. At lunch.
What if businesses and schools took seriously the existence of
nap zones? No meetings or classes would ever be scheduled at the
time when the process C and process S curves are flat-lined. No
high-demand presentations and no critical exams would be assigned
anywhere near the collision of these two curves. Instead, there would
be deliberately planned downshifts. Naps would be accorded the
same deference that businesses reluctantly treat lunch, or even potty
breaks: a necessary nod to an employee’s biological needs. Companies
would create a designated space for employees to take one half-hour
nap each workday. The advantage would be straightforward. People
hired for their intellectual strength would be allowed to keep that
strength in tip-top shape. “What other management strategy will
improve people’s performance 34 percent in just 26 minutes?” says
Mark Rosekind, the NASA scientist who conducted that eye-opening
research on naps and pilot performance.
Try sleeping on it
Given the data about a good night’s rest, organizations might
tackle their most intractable problems by having the entire “solving
team” go on a mini-retreat. Once arrived, employees would be
presented with the problem and asked to think about solutions. But
they would not start coming to conclusions, or even begin sharing
ideas with each other, before they had slept about eight hours.
When they awoke, would the same increase in problem-solving rates
available in the lab also be available to that team? We ought to find
out.

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Summary
Rule #7
Sleep well, think well.
The brain is in a constant state of tension between
•
•
cells and chemicals that try to put you to sleep and cells
and chemicals that try to keep you awake.
The neurons of your brain show vigorous rhythmical
•
•
activity when you’re asleep—perhaps replaying what you
learned that day.
People vary in how much sleep they need and when
•
•
they prefer to get it, but the biological drive for an
afternoon nap is universal.
Loss of sleep hurts attention, executive function,
•
•
working memory, mood, quantitative skills, logical
reasoning, and even motor dexterity.
Get more at www.brainrules.net

177. stress
Rule #8
Stressed brains don’t learn the same way.

179. it is, by any measure, a thoroughly rotten experiment.
Here is this beautiful German shepherd, lying in
one corner of a metal box, whimpering. He is receiving
painful electric shocks, stimuli that should leave him howling in
pain. Oddly enough, the dog could easily get out. The other side of
the box is perfectly insulated from shocks, and only a low barrier
separates the two sides. Though the dog could jump over to safety
when the whim strikes him, the whim doesn’t strike him. Ever. He
just lies down in the corner of the electric side, whimpering with
each jarring jolt. He must be physically removed by the experimenter
to be relieved of the experience.
What has happened to that dog?
A few days before entering the box, the animal was strapped to a
restraining harness rigged with electric wires, inescapably receiving
the same painful shock day and night. And at first he didn’t just
stand there taking it, he reacted. He howled in pain. He urinated.
He strained mightily against his harness in an increasingly desperate

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attempt to link some behavior of his with the cessation of the pain.
But it was no use. As the hours and even days ticked by, his resistance
eventually subsided. Why? The dog began to receive a very clear
message: The pain was not going to stop; the shocks were going to
be forever. There was no way out. Even after the dog had been released
from the harness and placed into the metal box with the escape route,
he could no longer understand his options. Indeed, most learning
had been shut down, and that’s probably the worst part of all.
Those of you familiar with psychology already know I am
describing a famous set of experiments begun in the late 1960s
by legendary psychologist Martin Seligman. He coined the
term “learned helplessness” to describe both the perception of
inescapability and its associated cognitive collapse. Many animals
behave in a similar fashion where punishment is unavoidable, and
that includes humans. Inmates in concentration camps routinely
experienced these symptoms in response to the horrid conditions
of the internment, and some camps even gave it the name Gamel,
derived from the colloquial German word Gameln, which literally
means “rotting.” Perhaps not surprisingly, Seligman has spent the
balance of his career studying how humans respond to optimism.
What is so awful about severe, chronic stress that it can wreak
such extraordinary changes in behavior? Why is learning so radically
altered? Let’s begin with a definition of stress, talk about biological
responses, and then move to the relationship between stress and
learning. Along the way, we will talk about marriage and parenting,
about the workplace, and about the first and only time I ever heard
my mother, a fourth-grade teacher, swear. It was her first real
encounter with learned helplessness.
terror and titillation
We begin with an attempt at definitions, and, as is true of all
things cognitive, we suddenly run into turbulence. First, not all
stress is the same. Certain types of stress really hurt learning, but

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some types of stress boost learning. Second, it’s difficult to detect
when someone is experiencing stress. Some people love skydiving
for recreation; it’s others’ worst nightmare. Is jumping out of an
airplane inherently stressful? The answer is no, and that highlights
the subjective nature of stress.
The body isn’t of much help in providing a definition, either.
There is no unique grouping of physiological responses capable of
telling a scientist whether or not you are experiencing stress. The
reason? Many of the same mechanisms that cause you to shrink in
horror from a predator are also used when you are having sex—or
even while you are consuming your Thanksgiving dinner. To your
body, saber-toothed tigers and orgasms and turkey gravy look
remarkably similar. An aroused physiological state is characteristic of
both stress and pleasure.
So what’s a scientist to do? A few years ago, gifted researchers
Jeansok Kim and David Diamond came up with a three-part
definition that covers many of the bases. In their view, if all three are
happening simultaneously, a person is stressed.
Part one: There must be an aroused physiological response to the
stress, and it must be measurable by an outside party. I saw this in
obvious fashion the first time my then 18-month-old son encountered
a carrot on his plate at dinner. He promptly went ballistic: He
screamed and cried and peed in his diaper. His aroused physiological
state was immediately measurable by his dad, and probably by anyone
else within a half mile of our kitchen table.
Part two: The stressor must be perceived as aversive. This can be
assessed by a simple question: “If you had the ability to turn down
the severity of this experience, or avoid it altogether, would you?” It
was obvious where my son stood on the matter. Within seconds, he
took the carrot off his plate and threw it on the floor. Then he deftly
got down off his chair and tried to stomp on the predatory vegetable.
The avoidance question was answered in full.
Part three: The person must not feel in control of the stressor.

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Like a volume knob on some emotional radio, the more the loss of
control, the more severe the stress is perceived to be. This element
of control and its closely related twin, predictability, lie at the heart
of learned helplessness. My son reacted as strongly as he did in part
because he knew I wanted him to eat the carrot, and he was used
to doing what I told him to do. Control was the issue. Despite my
picking up the carrot, washing it, then rubbing my tummy while
enthusiastically saying “yum, yum,” he was having none of it. Or,
more important, he was wanting to have none of it, and he thought
I was going to make him have all of it. Out-of-control carrot equaled
out-of-control behavior.
When you find this trinity of components working together,
you have the type of stress easily measurable in a laboratory setting.
When I talk about stress, I am usually referring to situations like
these.
flooding the system
You can feel your body responding to stress: Your pulse races,
your blood pressure rises, and you feel a massive release of energy.
That’s the famous hormone adrenaline at work. It’s spurred into
action by your brain’s hypothalamus, that pea-size organ sitting
almost in the middle of your head. When your sensory systems
detect stress, the hypothalamus reacts by sending a signal to your
adrenal glands, lying far away on the roof of your kidneys. The glands
immediately dump bucketloads of adrenaline into your bloodstream.
The overall effect is called the fight or flight response.
But there’s a less famous hormone at work, too—also released
by the adrenals, and just as powerful as adrenalin. It’s called cortisol.
You can think of it as the “elite strike force” of the human stress
response. It’s the second wave of our defensive reaction to stressors,
and, in small doses, it wipes out most unpleasant aspects of stress,
returning us to normalcy.
Why do our bodies need to go through all this trouble? The

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answer is very simple. Without a flexible, immediately available,
highly regulated stress response, we would die. Remember, the
brain is the world’s most sophisticated survival organ. All of its many
complexities are built toward a mildly erotic, singularly selfish goal:
to live long enough to thrust our genes on to the next generation. Our
reactions to stress serve the live-long-enough part of that goal. Stress
helps us manage the threats that could keep us from procreating.
And what kinds of sex-inhibiting threats did we experience in our
evolutionary toddlerhood? It’s a safe bet they didn’t involve worrying
about retirement. Imagine you were a cave person roaming around
the east African savannah. What kinds of concerns would occupy
your waking hours? Predators would make it into your top 10 list.
So would physical injury, which might very well come from those
predators. In modern times, a broken leg means a trip to the doctor.
In our distant past, a broken leg often meant a death sentence. The
day’s climate might also be a concern, the day’s offering of food
another. A lot of very immediate needs rise to the surface, needs that
have nothing to do with old age.
Why immediate? Most of the survival issues we faced in our
first few million years did not take hours, or even minutes, to settle.
The saber-toothed tiger either ate us or we ran away from it—or a
lucky few might stab it, but the whole thing was usually over in less
than half a minute. Consequently, our stress responses were shaped
to solve problems that lasted not for years, but for seconds. They
were primarily designed to get our muscles moving us as quickly as
possible, usually out of harm’s way. You can see the importance of
this immediate reaction by observing people who cannot mount a
thorough and sudden stress response. If you had Addison’s disease,
for example, you would be unable to raise your blood pressure in
response to severe stress, such as being attacked by a mountain lion.
Your blood pressure would drop catastrophically, probably putting
you into a state of debilitating shock. You would become limp. Then
you would become lunch.

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These days, our stresses are measured not in moments with
mountain lions, but in hours, days, and sometimes months with
hectic workplaces, screaming toddlers, and money problems. Our
system isn’t built for that. And when moderate amounts of hormone
build up to large amounts, or when moderate amounts of hormone
hang around too long, they become quite harmful. That’s how an
exquisitely tuned system can become deregulated enough to affect a
dog in a metal crate—or a report card, or a performance review.
from sniffles to forgetfulness
Stress can hurt more than our brains. In the short term, acute
stress can boost cardiovascular performance—the probable source
of those urban legends about grandmothers lifting one end of a car
to rescue their grandchildren stuck under the wheels. Over the long
term, however, too much adrenaline stops regulating surges in your
blood pressure. These unregulated surges create sandpaper-like rough
spots on the insides of your blood vessels. The spots turn into scars,
which allow sticky substances in the blood to build up there, clogging
your arteries. If it happens in the blood vessels of your heart, you
get a heart attack; in your brain, you get a stroke. Not surprisingly,
people who experience chronic stress have an elevated risk of heart
attacks and strokes.
Stress also affects our immune response. At first, the stress
response helps equip your white blood cells, sending them off to fight
on the body’s most vulnerable fronts, such as the skin. Acute stress
can even make you respond better to a flu shot. But chronic stress
reverses these effects, decreasing your number of heroic white-blood-
cell soldiers, stripping them of their weapons, even killing them
outright. Over the long term, stress ravages parts of the immune
system involved in producing antibodies. Together, these can cripple
your ability to fight infection. Chronic stress also can coax your
immune system to fire indiscriminately, even at targets that aren’t
shooting back—like your own body.

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Not surprisingly, people who experience chronic stress are
sick more often. A lot more often. One study showed that stressed
individuals were three times as likely to suffer from the common
cold. People were especially vulnerable to the cold-producing virus
if the stressors were social in nature and lasted more than a month.
They also are more likely to suffer from autoimmune disorders, such
as asthma and diabetes.
To show how sensitive the immune system can be to stress,
you need look no further than an experiment done with the drama
department at UCLA. If you can imagine having to think all day of
the most depressing things that have ever happened in your life, then
acting out these feelings in front of scientists while they are taking
your blood, you will have a pretty good idea of this Transylvanian
research exercise. During the experiment, the actors practiced
method acting (which asks you, if the scene calls for you to be scared,
to think of something frightening, then recite your lines while
plumbing those memories). One group performed using only happy
memories, the other only sad. The researchers monitored their
blood samples, continually looking for immune “competence.” Those
people who had been working with uplifting scripts all day long had
healthy immune systems. Their immune cells were plentiful, happy,
readily available for work. Those people who had been working
with depressing scripts all day long showed something unexpected:
a marked decrease in immune responsiveness. Their immune cells
were not plentiful, not as robust, not as available for work. These
actors were much more vulnerable to infection.
The brain is just as influenced by stress as the immune system is.
The hippocampus, that fortress of human memory, is studded with
cortisol receptors like cloves in a ham. This makes it very responsive
to stress signals. If the stress is not too severe, the brain performs
better. Its owner can solve problems more effectively and is more
likely to retain information. There’s an evolutionary reason for this.
Life-threatening events are some of the most important experiences

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we can remember. They happened with lightning speed in the
savannah, and those who could commit those experiences to memory
the fastest (and recall them accurately with equal speed) were more
apt to survive than those who couldn’t. Indeed, research shows that
memories of stressful experiences are formed almost instantaneously
in the human brain, and they can be recalled very quickly during
times of crises.
If the stress is too severe or too prolonged, however, stress begins
to harm learning. The influence can be devastating. You can see the
effects of stress on learning in everyday life. Stressed people don’t
do math very well. They don’t process language very efficiently.
They have poorer memories, both short and long forms. Stressed
individuals do not generalize or adapt old pieces of information
to new scenarios as well as non-stressed individuals. They can’t
concentrate. In almost every way it can be tested, chronic stress hurts
our ability to learn. One study showed that adults with high stress
levels performed 50 percent worse on certain cognitive tests than
adults with low stress. Specifically, stress hurts declarative memory
(things you can declare) and executive function (the type of thinking
that involves problem-solving). Those, of course, are the skills needed
to excel in school and business.
the villain, the hero
The biology behind this obvious assault on our intelligences can
be described as a tale of two molecules, one a villain, the other a hero.
The villain is the previously discussed cortisol, part of a motley crew
of hormones going by the tongue-twisting name of glucocorticoids
(I’ll call them stress hormones). These hormones are secreted by
the adrenal glands, which lie like a roof on top of your kidneys. The
adrenal glands are so exquisitely responsive to neural signals, they
appear to have once been a part of your brain that somehow fell off
and landed in your mid-abdomen.
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boatloads of the stuff are given free access to your central nervous
system. That’s what’s going on when you experience chronic stress.
Stress hormones seem to have a particular liking for cells in the
hippocampus, and that’s a problem, because the hippocampus is
deeply involved in many aspects of human learning. Stress hormones
can make cells in the hippocampus more vulnerable to other stresses.
Stress hormones can disconnect neural networks, the webbing
of brain cells that act like a safety deposit vault, storing your most
precious memories. They can stop the hippocampus from giving
birth to brand-new baby neurons. Under extreme conditions, stress
hormones can even kill hippocampal cells. Quite literally, severe
stress can cause brain damage in the very tissues most likely to help
your children pass their SATs.
The brain seems to be aware of all this and has supplied our story
not only with a villain but also with a hero. We met this champion
back in the Exercise chapter. It’s the Brain Derived Neurotrophic
Factor. BDNF is the premier member of the powerful group of
proteins called neurotrophins. BDNF in the hippocampus acts like a
standing military armed with bags of Miracle Gro, keeping neurons
alive and growing in the presence of hostile action. As long as there
is enough BDNF around, stress hormones cannot do their damage.
As I said, BDNF is a hero. How, then, does the system break down?
The problem begins when too many stress hormones hang
around in the brain too long, a situation you find in chronic stress,
especially of the learned helplessness variety. As wonderful as the
BDNF fertilizer armies are, it is possible to overwhelm them if they
are assaulted with a sufficiently strong (and sufficiently lengthy)
glucocorticoid siege. Like a fortress overrun by invaders, enough
stress hormones will eventually overwhelm the brain’s natural
defenses and wreak their havoc. In sufficient quantities, stress
hormones are fully capable of turning off the gene that makes
BDNF in hippocampal cells. You read that right: Not only can they
overwhelm our natural defenses, but they can actually turn them off.

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The damaging effects can be long-lasting, a fact easily observed when
people experience catastrophic stress.
You might recall the bodyguard who was in the car with Princess
Diana on the night of her death. To this day, he cannot remember
the events several hours before or after the crash. That is a typical
response to severe trauma. Its lighter cousin, forgetfulness, is quite
common when the stress is perhaps less severe but more pervasive.
One of the most insidious effects of prolonged stress is that
it pushes people into depression. I don’t mean the type of “blues”
people can experience as a normal part of daily living. Nor do I
mean the type resulting from tragic circumstance, such as the death
of a relative. I am talking about the kind of depression that causes
as many as 800,000 people a year to attempt suicide. It is a disease
every bit as organic as diabetes, and often deadlier. Chronic exposure
to stress can lead you to depression’s doorstep, then push you
through. Depression is a deregulation of thought processes, including
memory, language, quantitative reasoning, fluid intelligence,
and spatial perception. The list is long and familiar. But one of its
hallmarks may not be as familiar, unless you are in depression. Many
people who feel depressed also feel there is no way out of their
depression. They feel that life’s shocks are permanent and things will
never get better. Even when there is a way out—treatment is often
very successful—there is no perception of it. They can no more argue
their way out of a depression than they could argue their way out of a
heart attack.
Clearly, stress hurts learning. Most important, however, stress
hurts people.
a genetic buffer
In a world as complex as the brain, is the relationship between
stress and learning that straightforward? For once, the answer is yes.
Out-of-control stress is bad news for the brains of most people. Of
course, most doesn’t mean all. Like oddly placed candles in a dark

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room, some people illuminate corners of human behavior with
unexpected clarity. They illustrate the complexity of environmental
and genetic factors.
Jill was born into an inner-city home. Her father began having sex
with Jill and her sister during their preschool years. Her mother was
institutionalized twice because of what used to be termed “nervous
breakdowns.” When Jill was 7 years old, her agitated dad called a
family meeting in the living room. In front of the whole clan, he put
a handgun to his head, said, “You drove me to this,” then blew his
brains out. The mother’s mental condition continued to deteriorate,
and she revolved in and out of mental hospitals for years. When
Mom was home, she would beat Jill. Beginning in her early teens,
Jill was forced to work outside the home to help make ends meet.
As Jill got older, we would have expected to see deep psychiatric
scars, severe emotional damage, drugs, maybe even a pregnancy or
two. Instead, Jill developed into a charming and quite popular young
woman at school. She became a talented singer, an honor student,
and president of her high school class. By every measure, she was
emotionally well-adjusted and seemingly unscathed by the awful
circumstances of her childhood.
Her story, published in a leading psychiatric journal, illustrates
the unevenness of the human response to stress. Psychiatrists long
have observed that some people are more tolerant of stress than
others. Molecular geneticists are beginning to shed light on the
reasons. Some people’s genetic complement naturally buffers them
against the effects of stress, even the chronic type. Scientists have
isolated some of these genes. In the future, we may be able to tell
stress-tolerant from stress-sensitive individuals with a simple blood
test, looking for the presence of these genes.
the tipping point
How can we explain both the typical responses to stress, which
can be quite debilitating, and the exceptions? For that, we turn to a

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senior scientist, Bruce McEwen, an elder statesman, smart, always in
a suit and tie.
McEwen developed a powerful framework that allows us to
understand all the various ways humans respond to stress. He gave
it a name straight out of a Star Trek engineering manual: allostasis.
Allo is from a Greek word meaning variable; stasis means a condition
of balance. The idea is that there are systems that help keep the
body stable by changing themselves. The stress system in the human
body, and its many intricate subsystems, is one of those. The brain
coordinates these body-wide changes—behavior included—in
response to potential threats.
This model says that stress, left alone, is neither harmful nor
toxic. Whether stress becomes damaging is the result of a complex
interaction between the outside world and our physiological capacity
to manage the stress. Your body’s reaction to stress depends on the
stress, on its length and severity, and on your body. There’s a point
where stress becomes toxic, and McEwen calls it the allostatic load.
I know it as the first time, and only time, I ever heard my mother
use profanity. I also know it as the time I got the worst grade in my
academic career. We all have stories that illustrate the concrete
effects of stress on real life.
As you may recall, my mother was a fourth-grade teacher. I was
upstairs in my room, unbeknownst to my mother, who was upstairs
in her room grading papers. She was grading one of her favorite
students, a sweet, brown-haired little wisp of a girl I will call Kelly.
Kelly was every teacher’s dream kid: smart, socially poised, blessed
with a wealth of friends. Kelly had done very well in the first half of
the school year.
The second half of the school year was another story, however.
My mother sensed something was very wrong the moment Kelly
walked into class after Christmas break. Her eyes were mostly
downcast, and within a week she had gotten into her first fight. In
another week, she got her first C on an exam, and that would prove

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to be the high point, as her grades for the rest of the year fluttered
between D’s and F’s. She was sent to the principal’s office numerous
times, and my mother, exasperated, decided to find out what caused
this meltdown. She learned that Kelly’s parents had decided to get a
divorce over Christmas and that the family conflicts, from which the
parents valiantly had insulated Kelly, had begun spilling out into the
open. As things unraveled at home, things also unraveled at school.
And on that snowy day, when my mother gave Kelly her third straight
D in spelling, my mother also swore:
“Dammit!” she said, nearly under her breath. I froze as she
shouted, “THE ABILITY OF KELLY TO DO WELL IN MY CLASS
HAS NOTHING TO DO WITH MY CLASS!”
She was, of course, describing the relationship between home
life and school life, a link that has frustrated teachers for a long time.
One of the greatest predictors of performance in school turns out to
be the emotional stability of the home.
stress in the home
I want to focus on stress in the home because it is profoundly
related to kids’ ability to do well in the classroom and, when they
grow up, in the workforce.
Consider the all-too common case of kids witnessing their
parents fighting. The simple fact is that children find unresolved
marital conflict deeply disturbing. Kids cover their ears, stand
motionless with clenched fists, cry, scowl, ask to leave, beg parents
to stop. Study after study has shown that children—some as young
as 6 months—react to adult arguments physiologically, such as with
a faster heart rate and higher blood pressure. Kids of all ages who
watch parents constantly fight have more stress hormones in their
urine. They have more difficulty regulating their emotions, soothing
themselves, focusing their attention on others. They are powerless to
stop the conflict, and the loss of control is emotionally crippling. As
you know, control is a powerful influence on the perception of stress.

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This loss can influence many things in their lives, including their
schoolwork. They are experiencing allostatic load.
I have firsthand experience with the effects of stress on grades. I
was a senior in high school when my mother was diagnosed with the
disease that would eventually kill her. She had come home late from
a doctor’s visit and was attempting to fix the family dinner. But when
I found her, she was just staring at the kitchen wall. She haltingly
related the terminal nature of her medical condition and then, as
if that weren’t enough, unloaded another bombshell. My dad, who
had some prior knowledge of Mom’s condition, was not handling
the news very well and had decided to file for divorce. I felt as if I
had just been punched in the stomach. For a few seconds I could not
move. School the next day, and for the next 13 weeks, was a disaster. I
don’t remember much of the lectures. I only remember staring at my
textbooks, thinking that this amazing woman had taught me to read
and love such books, that we used to have a happy family, and that all
of this was coming to an end. What she must have been feeling, much
worse than I could ever fathom, she never related. Not knowing how
to react, my friends soon withdrew from me even as I withdrew from
them. I lost the ability to concentrate, my mind wandering back to
childhood. My academic effort became a train wreck. I got the only
D I would ever get in my school career, and I couldn’t have cared less.
Even after all these years, it is still tough to write about that high
school moment. But it easily illustrates this second, very powerful
consequence of stress, underscoring with sad vengeance our Brain
Rule: Stressed brains do not learn the same way as non-stressed
brains. My grief at least had an end-point. Imagine growing up in an
emotionally unstable home, where the stress seems never-ending.
Given that stress can powerfully affect learning, one might predict
that children living in high-anxiety households would not perform as
well academically as kids living in more nurturing households.
That is exactly what researchers have found. Marital stress at
home can negatively affect academic performance in almost every

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way measurable, and at nearly any age. Initial studies focused on
grade-point averages over time. They reveal striking disparities
of achievement between divorce and control groups. Subsequent
investigations showed that even when a couple stays together,
children living in emotionally unstable homes get lower grades.
(Careful subsequent investigations showed that it was the presence
of overt conflict, not divorce, that predicted grade failure.) They also
do worse on standardized math and reading tests.
The stronger the degree of conflict, the greater the effect on
performance. Teachers typically report that children from disrupted
homes rate lower in both aptitude and intelligence. Such children
are three times as likely to be expelled from school or to become
pregnant as teenagers, and five times as likely to live in poverty.
As social activist Barbara Whitehead put it, writing for the Atlantic
Monthly: “Teachers find many children emotionally distracted, so
upset and preoccupied by the explosive drama of their own family
lives that they are unable to concentrate on such mundane matters as
multiplication tables.”
Physical health deteriorates; absenteeism and truancy increase.
The absenteeism may occur because stress is depleting the immune
system, which increases the risk of infection. Though the evidence is
not as conclusive, a growing body of data suggests that children living
in hostile environments are at greater risk for certain psychiatric
disorders, such as depression and anxiety disorders. Such disorders
can wreak havoc on cognitive processes important to successful
academic performance. As children grow up, the effects of childhood
stress can stay with them. Indeed, performance can take a negative
hit regardless of one’s age, even if you were a previously high
functioning and much admired employee, like Lisa Nowak.
stress at work
You may have heard of Lisa Nowak. She is a lethal combat
pilot, decorated electronics warfare specialist, pretty, smart. The

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government spent millions of dollars training her to be an astronaut.
She was also a mother with two kids on the verge of divorcing her
husband one month before her biggest professional assignment:
mission control specialist for a shuttle mission. Talk about built-up
stress. She put some weapons in her automobile, grabbed a disguise,
even packed up a bunch of adult diapers so she didn’t have to stop
to use a bathroom. She then drove virtually nonstop from Orlando
to Houston, allegedly to kidnap her target, a woman she thought
was a threat to a fellow astronaut to whom she had taken a fancy.
Instead of serving as the lead for one of America’s most technically
challenging jobs, this highly skilled engineer is awaiting trial on
attempted kidnapping and burglary charges. She will probably never
fly again, which makes this sad story nearly heartbreaking. It also
makes the money spent on her training a colossal waste. But those
few million dollars are miniscule compared with the cost of stress on
the workplace as a whole.
Stress attacks the immune system, increasing employees’ chances
of getting sick. Stress elevates blood pressure, increasing the risk of
heart attack, stroke, and autoimmune diseases. That directly affects
health-care and pension costs. Stress is behind more than half of
the 550 million working days lost each year because of absenteeism.
Stressed employees tend to avoid coming to work at the slightest
excuse, and they often show up late. Yet executives often give stress
the shortest shrift. The Centers for Disease Control and Prevention
asserts that a full 80 percent of our medical expenditures are now
stress-related. In a work force where 77 percent report being burned
out, this translates into a lot of cortisol, a lot of missed meetings, and
a lot of trips to the doctor. That’s not all. Prolonged stress can cause
depression, which alters the ability to think—a direct assault on a
corporation’s intellectual capital. This injury to business productivity
is threefold.
First, depression hobbles the brain’s natural improvisatory
instincts the way arthritis hobbles a dancer. Fluid intelligence,

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problem-solving abilities (including quantitative reasoning), and
memory formation are deeply affected by depression. The result is
an erosion of innovation and creativity, just as biochemically real as
if we were talking about joints and muscles. In a knowledge-based
economy where intellectual dexterity is often the key to survival,
that’s bad news for competitiveness, shareholder value, and the
bottom line. In fact, the cost of depression to the work force in 1990
was estimated to be $53 billion. The loss of productivity contributed
the most, about $33 billion of the total.
Second, those same people who have lost their creativity incur
more health-care expenses. Thus, not only does stress reduce
the contributions valuable employees can make, but those same
employees begin to cannibalize their company’s internal resources.
And it’s not just mental-health expenditures. Depressed individuals
are at increased risk for a number of other diseases.
Third, people who burn out are often fired, if they don’t leave
on their own. Turnover further disrupts productivity, plus sets off a
costly recruiting and training effort. The ugly truth is that any assault
on human brain cells is an assault on competitiveness. The final tab?
Statistical analyses from many studies form the same dismal picture.
Stress causes companies to lose between $200 billion and $300
billion a year—as much as $75 billion of red ink a quarter.
Three things matter in determining whether a workplace
is stressful: the type of stress, a balance between occupational
stimulation and boredom, and the condition of the employee’s home
life. Business professionals have spent a long time studying what
types of stress make people less productive and, not surprisingly,
have arrived at the same conclusion that Marty Seligman’s German
shepherds did: Control is critical. The perfect storm of occupational
stress appears to be a combination of two malignant facts: a) a great
deal is expected of you and b) you have no control over whether you
will perform well. Sounds like a formula for learned helplessness to
me.

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On the positive side, restoration of control can return groups to
productivity. In one instance, a for-profit consented to be studied
after agreeing to institute a control-based stress management
program. At the end of two years, the unit had saved almost $150,000
in workers’ compensation costs alone. The cost of deploying the
stress management program? About $6,000. And just 16 hours of the
program reduced toxic blood pressure levels for employees diagnosed
with hypertension.
Control isn’t the only factor in productivity. Employees on an
assembly line, doing the same tired thing day after day, are certainly
in control of their work processes. But the tedium can be a source
of brain-numbing stress. What spices things up? Studies show
that a certain amount of uncertainty can be good for productivity,
especially for bright, motivated employees. What they need is a
balance between controllability and uncontrollability. Slight feelings
of uncertainty may cause them to deploy unique problem-solving
strategies.
The third characteristic, if you are a manager, is none of your
business. I am talking about the effects of family life on business
life. There’s no such thing as a firewall between personal issues and
work productivity. That’s because we can’t have two brains we can
interchange depending upon whether we are in our office or in our
bedroom. Stress in the workplace affects family life, causing more
stress in the family. More stress in the family causes more stress
at work, which in turn gets brought home again. It’s a deadly, self-
feeding spiral, and researchers call it “work-family conflict.” So you
may have the most wonderful feelings about autonomy at work, and
you may have tremendous problem-solving opportunities with your
colleagues. But if your home life is a wreck, you can still suffer the
negative effects of stress, and so can your employer.
Whether we look at school performance or job performance,
we keep running into the profound influence of the emotional
stability of the home. Is there anything we can do about something

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so fundamentally personal, given that its influence can be so terribly
public? The answer, surprisingly, may be yes.
marriage intervention
Famed marriage researcher John Gottman can predict the
future of a relationship within three minutes of interacting with the
couple. His ability to accurately forecast marital success or failure is
close to 90 percent. His track record is confirmed by peer-reviewed
publications. He may very well hold the future of the American
education and business sectors in his hands.
How is he so successful? After years of careful observation,
Gottman isolated specific marital behaviors—both positive and
negative—that hold most of the predictive power. But this research
was ultimately unsatisfying to a man like Gottman, akin to telling
someone they have a life-threatening illness but not being able to
cure them. And so the next step in his research was to try to harness
some of that predictive knowledge to give a couple a better future.
Gottman devised a marriage intervention strategy based on his
decades of research. It focuses on improving the behaviors proven to
predict marital success and eliminating the ones proven to predict
failure. Even in its most modest forms, his intervention drops divorce
rates by nearly 50 percent.
What do his interventions actually do? They drop both the
frequency and severity of hostile interactions between husband and
wife. This return to civility has many positive side effects besides
marital reconstruction, especially if the couple has kids. The link
is direct. These days, Gottman says, he can predict the quality of a
relationship not only by examining the stress responses of the parents
but also by taking a urine sample of their children.
That last statement deserves some unpacking. Gottman’s
marriage research invariably put him in touch with couples who
were starting families. When these marriages started their transition
to parenthood, Gottman noticed that the couple’s hostile interactions

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skyrocketed. There were many causes, ranging from chronic sleep
deprivation to the increased demands of a helpless new family
member (little ones typically require that an adult satisfy some
demand of theirs about 3 times a minute). By the time the baby was
1 year old, marital satisfaction had plummeted 70 percent. At that
same point, the risk for maternal depression went from 25 percent
to a whopping 62 percent. The couples’ risk for divorce increased,
which meant American babies often were born into a turbulent
emotional world.
That single observation gave Gottman and fellow researcher
Alyson Shapiro an idea. What if he deployed his proven marital
intervention strategies to married couples while the wife was
pregnant? Before the hostility floodgates opened up? Before the
depression rates went through the roof? Statistically, he already
knew the marriage would significantly improve. The big question
concerned the kids. What would an emotionally stabilized
environment do to the baby’s developing nervous system? He decided
to find out.
The research investigation, deployed over several years, was
called Bringing Baby Home. It consisted of exposing expectant
couples to the marital interventions whether their marriages were
in trouble or not, and then assessing the development of the child.
Gottman and Shapiro uncovered a gold mine of information. They
found that babies raised in the intervention households didn’t
look anything like the babies raised in the controls. Their nervous
systems didn’t develop the same way. Their behaviors weren’t in
the same emotional universe. Children in the intervention groups
didn’t cry as much. They had stronger attention-shifting behaviors
and they responded to external stressors in remarkably stable ways.
Physiologically, the intervention babies showed all the cardinal signs
of healthy emotional regulation, while the controls showed all the
signs of unhealthy, disorganized nervous systems. The differences
were remarkable and revealed something hopeful and filled with

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common sense. By stabilizing the parents, Gottman and Shapiro were
able to change not only the marriage; they also were able to change
the child.
I think Gottman’s findings can change the world, starting with
report cards and performance evaluations.
ideas
What people do in their private life is their own business, of
course. Unfortunately, what people do in their private life often
affects the public. Consider the criminal history of a fellow who had
recently moved from Texas to a city in the Pacific Northwest. He
absolutely hated his new home and decided to leave. Stealing the
car of a neighbor (for the second time that month), he drove several
miles to the airport and ditched the car. He then found a way to fool
both the security officials and the gate managers and hopped a free
ride back to Texas. He accomplished this feat a few months shy of
his 10th
birthday. Not surprisingly, this boy comes from a troubled
home. This is a fairly recent event, but if something isn’t done soon,
the private issue of raising this child soon will become a very public
problem. And he is hardly alone. How can we capture our Brain Rule,
that stressed brains learn differently from non-stressed brains, and
change the way we educate, parent, and do business? I have thought
a lot about that.
Teach parents first
The current education system starts in first grade, typically
around age 6. The curriculum is a little writing, a little reading, a
little math. The teacher is often a complete stranger. And there is
something important missing. The stability of the home is completely
ignored, even though it is one of the greatest predictors of future
success at school. But what if we took its influence seriously?
My idea envisions an educational system where the first
students are not the children. The first students are the parents.

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The curriculum? How to create a stable home life, using Gottman’s
powerful, baby-nervous-system changing protocols. The intervention
could even start in a maternity ward, offered by a hospital (like a
Lamaze class, which takes just about as much time). There would be
a unique partnership between the health system and the education
system. And it makes education, from the beginning of a child’s life, a
family affair.
First grade would begin a week after birth. The amazing cognitive
abilities of infants, from language acquisition to the powerful need
for luxurious amounts of active playtime, are fully unleashed in a
curriculum designed just for them. (This is not a call to implement
products in the strange industry that seeks to turn babies into
Einsteins in the first year of life. Most of those products have not
been tested, and some have been shown to be harmful to learning.
My idea envisions a mature, rigorously tested pedagogy that does not
yet exist—one more reason for educators and brain scientists to work
together.) Along with this, parents would take an occasional series
of marital refresher courses, just to ensure the stability of the home.
Can you imagine what a child might look like academically after
years of thriving in an emotionally stable environment? The child
flourishes in this fantasy.
No hospitals or schools currently offer these interventions to
the future students of America, and there is no formal curriculum
for harnessing the cognitive horsepower of the under-solid-food
crowd. But it could be developed and tested, beginning right this
minute. The best shot would come from collaborative experiments
between brain scientists and education scientists. All one needs is a
cooperative educational will, and maybe a sense of adventure.
Free family counseling, child care
Historically, people have done their best work—sometimes
world-changing work—in their first few years after joining the work
force. In the field of economics, most Nobel Prize-winning research

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is done in the first 10 years of the recipient’s career. Albert Einstein
published most of his creative ideas at the ripe old age of 26. It’s no
wonder that companies want to recruit young intellectual talent.
The problem in today’s economy is that people are typically
starting a family at the very time they are also supposed to be
doing their best work. They are trying to be productive at some of
the most stressful times of their lives. What if companies took this
unhappy collision of life events seriously? They could offer Gottman’s
intervention as a benefit for every newly married, or newly pregnant,
employee. Would that reverse the negative flow of family stress that
normally enters the workplace at this time in a person’s life? Such an
intervention might enhance productivity and perhaps even generate
grateful, loyal employees.
Businesses also risk losing their best and brightest at this time, as
talented people are forced to make a terrible decision between career
and family. The decision is especially hard on women. In the 21st
century, we have invented two economic classifications: the child-
free class (people with no kids or without primary responsibility
for them) and the child-bound class (people who act as a main
caregiver). From a gender perspective, these categories have very
little symmetry. According to Claudia Goldin, Henry Lee Professor
of Economics at Harvard, women are overrepresented in the child-
bound category by nearly 9 to 1.
What if talented people didn’t have to choose between career
and family? What if businesses offered onsite child care just so they
could retain employees at the very time they are most likely to be
valuable? This obviously would affect women the most, which means
businesses immediately achieve more gender balance. Would such an
offering so affect productivity that the costs of providing child care
become offset by the gains? That’s a great research question. Not
only might businesses create more stable employees in the current
generation, they might be raising far healthier children for work in
the next.

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Power to the workers
Plenty of books discuss how to manage stress; some are confusing,
others extraordinarily insightful. The good ones all say one thing in
common: The biggest part of successful stress management involves
getting control back into your life. This means that a manager or
human-resources professional has a powerful predictive insight at his
or her disposal. To detect stress-related problems, one might simply
examine the situations where an employee feels the most helpless.
Questionnaires based on Jeansok Kim’s and David Diamond’s three-
pronged definition of stress could be developed that routinely assess
not the broad perception of aversion, but the narrower issue of
powerlessness. The next step would be to change the situation.
These are only a few of the possibilities that could be realized
if brain scientists and business professionals ever collaborated on
the biology of stress in the work force. It is possible their findings
would change the absentee rate of their employees, cut down on the
number of trips to the doctor, and reduce their insurance overhead.
As well as money saved, a great deal of creativity may be engendered
simply by routinely giving employees a way out—not from their jobs
but from the stress they experience in them.
It’s no coincidence that stress researchers, education scientists,
and business professionals come to similar conclusions about stress
and people. What’s astonishing is that we have known most of the
salient points since Marty Seligman stopped shocking his dogs in the
mid-1970s. It is time we made productive use of that horrible line of
research.

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Summary
Rule #8
Stressed brains
don’t learn the same way.
Your body’s defense system—the release of adrenaline
•
•
and cortisol—is built for an immediate response to a
serious but passing danger, such as a saber-toothed tiger.
Chronic stress, such as hostility at home, dangerously
deregulates a system built only to deal with short-term
responses.
Under chronic stress, adrenaline creates scars in your
•
•
blood vessels that can cause a heart attack or stroke, and
cortisol damages the cells of the hippocampus, crippling
your ability to learn and remember.
Individually, the worst kind of stress is the feeling that
•
•
you have no control over the problem—you are helpless.
Emotional stress has huge impacts across society, on
•
•
children’s ability to learn in school and on employees’
productivity at work.
Get more at www.brainrules.net

205. sensory
integration
Rule #9
Stimulate more of the senses.

207. every time tim sees the letter “E,” he also sees the color
red. He describes the color change as if suddenly forced
to look at the world through red-tinted glasses. When
Tim looks away from the letter “E,” his world returns to
normal, until he encounters the letter “O.” Then the world turns
blue. For Tim, reading a book is like living in a disco. For a long
time, Tim thought this happened to everyone. When he discovered
this happened to no one—at least not in his immediate circle—he
began to suspect he was crazy. Neither impression was correct,
of course. Tim is suffering—if that’s the right word—from a brain
condition called synesthesia. Though experienced by as many as 1
in 2,000 people (some think 1 in 200), it is a behavior about which
scientists know next to nothing. At first blush, there appears to be a
short-circuiting between the processing of various sensory inputs. If
scientists can nail down what happens when sensory processing goes
wrong, they may gain more understanding about what happens when
it goes right. So, synesthesia intrigues scientists interested in how

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the brain processes the world’s many senses. The effect that this has
on learning forms the heart of our Brain Rule: Stimulate more of the
senses at the same time.
saturday night fever
That you can detect anything has always seemed like a minor
miracle to me. On one hand, the inside of your head is a darkened,
silent place, lonely as a cave. On the other hand, your head crackles
with the perceptions of the whole world, sight, sound, taste, smell,
touch, energetic as a frat party. How could this be? For a long time,
nobody could figure it out. The Greeks didn’t think the brain did
much of anything. It just sat there like an inert pile of clay (indeed,
it does not generate enough electricity to prick your finger). Aristotle
thought the heart held all the action, pumping out rich, red blood
24 hours a day. The heart, he reasoned, harbored the “vital flame of
life,” a fire producing enough heat to give the brain a job description:
to act as a cooling device (he thought the lungs helped out, too).
Perhaps taking a cue from our Macedonian mentor, we still use the
word “heart” to describe many aspects of mental life.
How does the brain, brooding in its isolated bony chambers,
perceive the world? Consider this example: It is Friday night at
a New York club. The dance beat dominates, both annoying and
hypnotic, felt more than heard. Laser lights shoot across the room.
Bodies move. The smells of alcohol, fried food, and illegal smoking
mix in the atmosphere like a second sound track. In the corner, a
jilted lover is crying. There is so much information in the room, you
are beginning to get a headache, so you step out for a breath of fresh
air. The jilted lover follows you.
Snapshots like these illustrate the incredible amount of sensory
information your brain must process simultaneously. External
physical inputs and internal emotional inputs all are presented to
your brain in a never-ending fire hose of sensations. Dance clubs may
seem the extreme. Yet there may be no more information there than

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what you’d normally experience the next morning on the streets of
Manhattan. Faithfully, your brain perceives the screech of the taxis,
the pretzels for sale, the crosswalk signal, and the people brushing
past, just as it could hear the pounding beat and smell the cigarettes
last night. You are a wonder. And we in brain-science land are only
beginning to figure out how you do it.
Scientists often point to an experience called the McGurk
effect to illustrate sensory integration. Suppose researchers showed
you a video of a person saying the surprisingly ugly syllable “ga.”
Unbeknownst to you, the scientists had turned off the sound of the
original video and had dubbed the sound “ba” onto it. When the
scientist asks you to listen to the video with your eyes closed, you
hear “ba” just fine. But if you open your eyes, your brain suddenly
encounters the shape of the lips saying “ga” while your ears are
still hearing “ba.” The brain has no idea what to do with this
contradiction. So it makes something up. If you are like most people,
what you actually will hear when your eyes open is the syllable “da.”
This is the brain’s compromise between what you hear and what you
see—its need to attempt integration.
But you don’t have to be in a laboratory to show this. You can just
go to a movie. The actors you see speaking to each other on screen
are not really speaking to each other at all. Their voices emanate
from speakers cleverly placed around the room: some behind you,
some beside you; none centered on the actors’ mouths. Even so, you
believe the voices are coming from those mouths. Your eye observes
lips moving in tandem with the words your ears are hearing, and
the brain combines the experience to trick you into believing the
dialogue comes from the screen. Together, these senses create
the perception of someone speaking in front of you, when actually
nobody is speaking in front of you.
how the senses integrate
Analyses like these have led scientists to propose a series of

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theories about how the senses integrate. On one end of this large
continuum are ideas that remind me of the British armies during
the Revolutionary War. On the other end are ideas that remind
me of how the Americans fought them. The British, steeped in
the traditions of large European land wars, had lots of central
planning. The field office gathered information from leaders on the
battleground and then issued its commands. The Americans, steeped
in the traditions of nothing, used guerrilla tactics: on-the-ground
analysis and decision making prior to consultation with a central
command.
Take the sound of a single gunshot over a green field during that
war. In the British model of this experience, our senses function
separately, sending their information into the brain’s central
command, its sophisticated perception centers. Only in these centers
does the brain combine the sensory inputs into a cohesive perception
of the environment. The ears hear the rifle and generate a complete
auditory report of what just occurred. The eyes see the smoke
from the gun arising from the turf and process the information
separately, generating a visual report of the event. The nose, smelling
gunpowder, does the same thing. They each send their data to
central command. There, the inputs are bound together, a cohesive
perception is created, and the brain lets the soldier in on what he just
experienced. The processes can be divided into three steps:
step 1: sensation
This is where we capture the energies from our environment
pushing themselves into our orifices and rubbing against our skin.
The effort involves converting this external information into a brain-
friendly electrical language.
step 2: routing
Once the information is successfully translated into head-speak,
it is sent off to appropriate regions of the brain for further processing.

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The signals for vision, hearing, touch, taste and smell all have
separate, specialized places where this processing occurs. A region
called the thalamus, that well-connected, egg-shaped structure in the
middle of your “second brain,” helps supervise most of this shuttling.
step 3: perception
The various senses start merging their information. These
integrated signals are sent to increasingly complex areas of the brain
(actually called higher regions), and we begin to perceive what our
senses have given us. As we shall see shortly, this final step has both
bottom-up and top-down features.
The American model puts things very differently. Here the
senses work together from the very beginning, consulting and
influencing one another quite early in the process. As the ear and
eye simultaneously pick up gunshot and smoke, the two impressions
immediately confer with each other. They perceive that the events
are occurring in tandem, without conferencing with any higher
authority. The picture of a rifle firing over an open field emerges
in the observer’s brain. The steps are still sensation, routing, and
perception. But at each step, add “the signals begin immediately
communicating, influencing subsequent rounds of signal processing.”
The last stage, perception, is not where the integration begins. The
last step is where the integration culminates.
Which model is correct? The data are edging in the direction of
the second model, but the truth is that nobody knows how it works.
There are tantalizing suggestions that the senses actually help one
another, and in a precisely coordinated fashion. This chapter is
mostly interested in what happens after sensation and routing—after
we achieve perception.
bottoms up, tops down
We can see how important this last step is by looking at what

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happens when it breaks down. Oliver Sacks reports on a patient he
calls Dr. Richard who had lost various perceptual processing abilities.
There wasn’t anything wrong with Dr. Richard’s vision. He just
couldn’t always make sense of what he saw. When a friend walked
into the room and sat down on a chair, he did not always perceive the
person’s various body parts as belonging to the same body. Only when
the person got up out of the chair would he suddenly recognize them
as possessed by one person. If Dr. Richard looked at a photograph
of people at a football stadium, he would identify the same colors of
different people’s wardrobes as belonging “together” in some fashion.
He could not see such commonalities as belonging to separate people.
Most interesting, he could not always perceive multisensory stimuli
as belonging to the same experience. This could be observed when
Dr. Richard tried to watch someone speaking. He sometimes could
not make a connection between the motion of the speaker’s lips and
the speech. They would be out of sync; he sometimes reported the
experience as if watching a “badly dubbed foreign movie.”
Given the survival advantage to seeing the world as a whole,
scientists have been deeply concerned with the binding problem.
They ask: Once the thalamus has done its distribution duties,
what happens next? The information, dissected into sensory-size
pieces and flung widely across the brain’s landscape, needs to be
reassembled (something Dr. Richard was not very good at). Where
and how does information from different senses begin to merge in
the brain?
The where is easier than the how. We know that most of the
sophisticated stuff occurs in regions known as association cortices.
Association cortices are specialized areas that exist throughout
the brain, including the parietal, temporal, and frontal lobes. They
are not exactly sensory regions, and they are not exactly motor
regions, but they are exactly bridges between them (hence the name
association). Scientists think these regions use both bottom-up and
top-down processes to achieve perception. As the sensory signals

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ascend through higher and higher orders of neural processing, these
processes kick in. Here’s an example.
Author W. Somerset Maugham once said: “There are only
three rules for writing a novel. Unfortunately, nobody knows what
they are.” After your eyes read that sentence and the thalamus has
spattered various aspects of the sentence all over the inside of your
skull, bottom-up processors go to work. The visual system (which
we will say more about in the Vision chapter) is a classic bottom-
up processor. What happens? Feature detectors—which work like
auditors in an accounting firm—greet the sentence’s visual stimuli.
The auditors inspect every structural element in each letter of every
word in Maugham’s quote. They write a report, a visual conception of
letters and words. An upside-down arch becomes the letter “U.” Two
straight lines at right angles become the letter “T.” Combinations
of straight lines and curves become the word “three.” Written
information has a lot of visual features in it, and this report takes a
great deal of effort and time to organize. It is one of the reasons that
reading is a relatively slow way to put information into the brain.
Next comes top-down processing. This can be likened to a board
of directors reading the auditor’s report and then reacting to it. Many
comments are made. Sections are analyzed in light of pre-existing
knowledge. The board in your brain has heard of the word “three”
before, for example, and it has been familiar with the concept of
rules since you were familiar with anything. Some board members
even have heard of W. Somerset Maugham before, and they recall to
your consciousness a movie called Of Human Bondage, which you saw
in a film history course. Information is added to the data stream or
subtracted from the data stream. The brain can even alter the data
stream if it so chooses. And it so chooses a lot.
Such interpretive activity is the domain of top-down processing.
At this point, the brain generously lets you in on the fact that you
are perceiving something. Given that people have unique previous
experiences, they bring different interpretations to their top-down

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analyses. Thus, two people can see the same input and come away
with vastly different perceptions. It is a sobering thought. There is no
guarantee that your brain will perceive the world accurately, even if
other parts of your body can.
So, life is filled with the complex qualities of sounds, visual
images, shapes, textures, tastes, and odors, and the brain seeks to
simplify this world by adding more confusion. This requires large
groups of receptors, each one in charge of a particular sensory
attribute, to act simultaneously. For us to savor the richness and
diversity of perception, the central nervous system must integrate
the activity of entire sensory populations. It does this by pushing
electrical signals through an almost bewildering thicket of ever more
complex, higher neural assemblies. Finally, you perceive something.
survival by teamwork
There are many types of synesthesia—more than 50, according
to one paper. One of the strangest illustrates that even when the
brain’s wiring gets confused, the senses still work together. There are
some people who see a word and immediately experience a taste on
their tongue. This isn’t the typical mouth-watering response, such as
imagining the taste of a candy bar after hearing the word “chocolate.”
This is like seeing the word “sky” in a novel and suddenly tasting a
sour lemon in your mouth. A clever experiment showed that even
when the synesthete could not recall the exact word, he or she could
still get the taste, as long as there was some generalized description of
the missing word. Data like these illustrate that sensory processes are
wired to work together. Thus, the heart of the Brain Rule: Stimulate
more of the senses.
The evolutionary rationale for this observation is simple: Our
East African crib did not unveil its sensory information one sense at
a time during our development. It did not possess only visual stimuli,
like a silent movie, and then suddenly acquire an audio track a few
million years later, and then, later, smells and odors and textures. By

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the time we came out of the trees, our ancestors were encountering a
multisensory world and were already champions at experiencing it.
Some interesting experiments support these ideas. Several
years ago, scientists were able to peer in on the brain using fMRI
technology. They played a trick on their subjects: They showed a
video of someone speaking but completely turned off the sound.
When the researchers examined what the brain was doing, they
found that the area responsible for processing the sound, the auditory
cortex, was stimulated as if the person actually were hearing sound.
If the person was presented with a person simply “making faces,” the
auditory cortex was silent. It had to be a visual input related to sound.
Clearly, visual inputs influence auditory inputs, even with the sound
turned off.
In another experiment at about the same time, researchers
showed short flashes of light near the subjects’ hands, which were
rigged with a tactile stimulator. Sometimes researchers would turn
on the stimulator while the flash of light was occurring, sometimes
not. No matter how many times they did this, the visual portion of
the brain always lighted up the strongest when the tactile response
was paired with it. They could literally get a boost in the visual system
by introducing touch. This effect is called multimodal reinforcement.
Multiple senses affect our ability to detect stimuli, too. Most
people, for example, have a very hard time seeing a flickering light if
the intensity of the light is gradually decreased. Researchers decided
to test that threshold by precisely coordinating a short burst of sound
with the light flickering off. The presence of sound actually changed
the threshold. The subjects found that they could see the light way
beyond their normal threshold if sound was part of the experience.
These data show off the brain’s powerful integrative instincts.
Knowing that the brain cut its developmental teeth in an
overwhelmingly multisensory environment, you might hypothesize
that its learning abilities are increasingly optimized the more
multisensory the environment becomes. You might further

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hypothesize that the opposite is true: Learning is less effective in a
unisensory environment. That is exactly what you find, and it leads
to direct implications for education and business.
the learning link
Cognitive psychologist Richard Mayer probably has done more
than anybody else to explore the link between multimedia exposure
and learning. He sports a 10-megawatt smile, and his head looks
exactly like an egg (albeit a very clever egg). His experiments are
just as smooth: Divide the room into three groups. One group gets
information delivered via one sense (say, hearing), another the same
information from another sense (say, sight), and the third group the
same information delivered as a combination of the first two senses.
The groups in the multisensory environments always do better
than the groups in the unisensory environments. They have more
accurate recall. Their recall has better resolution and lasts longer,
evident even 20 years later. Problem-solving improves. In one study,
the group given multisensory presentations generated more than
50 percent more creative solutions on a problem-solving test than
students who saw unisensory presentations. In another study, the
improvement was more than 75 percent!
The benefits of multisensory inputs are physical as well. Our
muscles react more quickly, our threshold for detecting stimuli
improves, and our eyes react to visual stimuli more quickly. It’s not
just combinations of sight and sound. When touch is combined with
visual information, recognition learning leaps forward by almost 30
percent, compared with touch alone. These improvements are greater
than what you’d predict by simply adding up the unisensory data.
This is sometimes called supra-additive integration. In other words,
the positive contributions of multisensory presentations are greater
than the sum of their parts. Simply put, multisensory presentations
are the way to go.
Many explanations have been put forth to explain these

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consistent findings, and most involve working memory. You might
recall from Chapter 5 that working memory, formerly called short-
term memory, is a complex work space that allows the learner to
hold information for a short period of time. You might also recall its
importance to the classroom and to business. What goes on in the
volatile world of working memory deeply affects whether something
that is taught will also be learned.
All explanations about multisensory learning also deal with a
counter-intuitive property lurking at its mechanistic core: Extra
information given at the moment of learning makes learning better.
It’s like saying that if you carry two heavy backpacks on a hike instead
of one, you will accomplish your journey more quickly. This is the
“elaborative” processing that we saw in the chapter on short-term
memory. Stated formally: It is the extra cognitive processing of
information that helps the learner to integrate the new material with
prior information. Multisensory experiences are, of course, more
elaborate. Is that why they work? Richard Mayer thinks so. And so do
other scientists, looking mostly at recognition and recall.
One more example of synesthesia supports this, too. Remember
Solomon Shereshevskii’s amazing mental abilities? He could hear a
list of 70 words once, repeat the list back without error (forward or
backward), and then reproduce the same list, again without error, 15
years later. Shereshevskii had multiple categories of (dis)ability. He
felt that some colors were warm or cool, which is common. But he
also thought the number 1 was a proud, well-built man, and that the
number 6 was a man with a swollen foot, which was not common.
Some of his imaging was nearly hallucinatory. He related: “One time
I went to buy some ice cream … I walked over to the vendor and
asked her what kind of ice cream she had. ‘Fruit ice cream,’ she said.
But she answered in such a tone that a whole pile of coals, of black
cinders, came bursting out of her mouth, and I couldn’t bring myself
to buy any ice cream after she had answered that way.”
Shereshevskii clearly is in his own mental universe, but he

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illustrates a more general principle. Synesthetes almost universally
respond to the question “What good does this extra information
do?” with an immediate and hearty “It helps you remember.” Given
such unanimity, researchers have wondered for years if there is a
relationship between synesthesia and advanced mental ability.
There is. Synesthetes usually display unusually advanced memory
ability—photographic memory, in some cases. Most synesthetes
report the odd experiences as highly pleasurable, which may, by
virtue of dopamine, aid in memory formation.
rules for the rest of us
Over the decades, Mayer has isolated a number of rules for
multimedia presentation, linking what we know about working
memory with his own empirical findings on how multimedia
exposure affects human learning. Here are five of them in summary
form:
1) Multimedia principle: Students learn better from words and
pictures than from words alone.
2) Temporal contiguity principle: Students learn better when
corresponding words and pictures are presented simultaneously
rather than successively.
3) Spatial contiguity principle: Students learn better when
corresponding words and pictures are presented near to each other
rather than far from each on the page or screen.
4) Coherence principle: Students learn better when extraneous
material is excluded rather than included.
5) Modality principle: Students learn better from animation and
narration than from animation and on-screen text.
Though wonderfully empirical, these principles are relevant
only to combinations of two senses: hearing and vision. We have
three other senses also capable of contributing to the educational
environment. Beginning with the story of a talented combat veteran,
let’s explore what happens if we add just one more: smell.

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nosing it out
I once heard a story about a man who washed out of medical
school because of his nose. To understand his story, you have to
know something about the smell of surgery. And you have to have
killed somebody. Surgery can be a smelly experience. When you cut
somebody’s body, you invariably cut their blood vessels. To keep the
blood from interfering with the operation, surgeons use a cauterizing
tool, hot as a soldering iron. It’s applied directly to the wound,
burning it shut, filling the room with the acrid smell of smoldering
flesh. Combat can smell the same way. And the medical student in
question was a Vietnam vet with heavy combat experience. He didn’t
seem to suffer any aversive effects when he came home. He had no
post-traumatic stress disorder, and he became a high-functioning
undergraduate, eventually accepted into medical school. But then the
former soldier started his first surgery rotation. Entering the surgical
suite, he promptly smelled the burning flesh from the cauterizer.
The smell brought back to mind the immediate memory of an enemy
combatant he had shot in the face, point blank, an experience he
had suppressed for years. The memory literally doubled him over.
He ran out of the room crying, the dying enemy’s strange gurgling
sounds ringing in his ears, the noises of the evacuation helicopters in
the distance. All that day, he relived the experience; later that night,
he began to recall in succession other equally terrible events. He
resigned from the program the next week.
This story illustrates something scientists have known for years:
Smell can evoke memory. It’s called the Proust effect. Marcel Proust,
the French author of the profoundly moving book Remembrance
of Things Past, talked freely 100 years ago about smells and their
ability to elicit long-lost memories. Typical experiments have
investigated the unusual ability of a smell to enhance retrieval. Two
groups of people might be assigned to see a movie together, for
example, and then told to report to the lab for a memory test. The

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control group goes into an unmanipulated room and simply takes
the test. The experimental group takes the test in a room flooded
with the smell of popcorn. The results are then compared, scoring
for number of events recalled, accuracy of events recalled, specific
characteristics, and so on. The results of the test can be astonishing.
Some researchers report that smell-exposed experimental groups can
accurately retrieve twice as many memories as the controls. Others
report a 20 percent improvement, still others only a 10 percent.
One way to react to these data is to say, “Wow.” Another is to
ask, “Why the disparity in results?” One big reason is that the results
depend on the type of memory being assessed and the methodology
employed to obtain them. For example, researchers have found that
certain types of memory are exquisitely sensitive to smells and other
types nearly impenetrable. Odors appear to do their finest work when
subjects are asked to retrieve the emotional details of a memory, as
our medical student experienced, or to retrieve autobiographical
memories. You get the best results if the smells are congruent.
A movie test in which the smell of gasoline is pumped into the
experimental room does not yield the same positive memory-retrieval
results as the smell of popcorn does.
Odors are not so good at retrieving declarative memory. You
can get smell to boost declarative scores, but only if the test subjects
are emotionally aroused—usually, that means stressed—before
the experiment begins. (For some reason, showing a film of young
Australian aboriginal males being circumcised is a favorite way to do
this). Recent tests, however, show that smell can improve declarative
memory recall during sleep, a subject we will take up in a moment.
Is there a reason why the Proust effect exists—why smell evokes
memory? There might be, but to understand it, we have to know a
little bit about how smell is processed in the brain.
Right between the eyes lies a patch of neurons about the size of
a large postage stamp. This patch is called the olfactory region. The
outer surface of this region, the one closest to the air in the nose, is

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the olfactory epithelium. When we sniff, odor molecules enter the
nose chamber and collide with nerves there. This in itself is amazing,
given that the chamber is always covered by a thick layer of snot.
Somehow these persistent biochemicals penetrate the mucus and
brush against little quill-like protein receptors that stud the nerves in
the olfactory epithelium. The receptors can recognize a large number
of smell-evoking molecules. When that happens, the neurons begin
to fire excitedly, and you are well on your way to smelling something.
The rest of the journey occurs in the brain. The now occupied nerves
of the olfactory epithelium chat like teenagers on a cell phone to a
group of nerves lying directly above them, in the olfactory bulb.
These nerves help sort out the signals sent to it by the epithelium.
Here comes the interesting part of the story. Every other sensory
system, at this point, must send a signal to the thalamus and ask
permission to connect to the rest of the brain—including the higher
levels where perception occurs. Not the nerves carrying information
about smell. Like an important head of state in a motorcade, smell
signals bypass the thalamus and go right to their brainy destinations,
no meddling middle-man required.
One of those destinations is the amygdala, and it is at this
point that the Proust effect begins to make some sense. As you
recall, the amygdala supervises not only the formation of emotional
experiences but also the memory of emotional experiences. Because
smell directly stimulates the amygdala, smell directly stimulates
emotions. Smell signals also head through the piriform cortex to the
orbitofrontal cortex, a part of your brain just above and behind your
eyes and deeply involved in decision making. So smell plays a role in
decision making. It is almost as if the odor is saying, “My signal is so
important, I am going to give you a memorable emotion. What are
you going to do about it?”
Smell signals appear to be in a real hurry to take these shortcuts,
so much so that olfactory receptor cells aren’t even guarded by a
protective barrier. This is different from most other sensory receptor

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cells in the human body. Visual receptor neurons in the retina are
protected by the cornea, for example. Receptor neurons that allow
hearing in our ears are protected by the eardrum. The only things
protecting receptor neurons for smell are boogers. Otherwise, they
are directly exposed to the air.
ideas
There is no question that multiple cues, dished up via different
senses, enhance learning. They speed up responses, increase
accuracy, improve stimulation detection, and enrich encoding at the
moment of learning. Yet we still aren’t harnessing these benefits on a
regular basis in our classrooms and boardrooms. Here are a couple of
ideas that come to mind.
Multisensory school lessons
As we learned in the Attention chapter, the opening moments of
a lecture are cognitive hallowed ground. It is the one time teachers
automatically have more student minds paying attention to them.
If presentations during that critical time were multisensory, overall
retention might increase. We discovered in the Memory chapters
that repeating information in timed intervals helps stabilize memory.
What if we introduced information as a multisensory experience,
and then repeated not only the information but also one of the
modes of presentation? The first re-exposure might be presented
visually, for example; the next, auditorially; the third, kinesthetically.
Would that encoding-rich schedule increase retention in real-world
environments, boosting the already robust influence of repetition?
And let’s not continue to neglect our other senses. We saw that
touch and smell are capable of making powerful contributions to the
learning process. What if we began to think seriously about how to
adopt them into the classroom, perhaps in combination with more
traditional learning presentations? Would we capture their boosting
effects, too?

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One study showed that a combination of smell and sleep
improved declarative-memory consolidation. The delightful
experiment used a card game my sons and I play on a regular basis.
The game involves a specialized 52-card deck we purchased at a
museum, resplendent with 26 pairs of animals. We turn all of the
cards face down, then start selecting two cards to find matches. It is a
test of declarative memory. The one with the most correct pairs wins
the game.
In the experiment, the control groups played the game normally.
But the experimental groups didn’t. They played the game in the
presence of rose scent. Then everybody went to bed. The control
groups were allowed to sleep unperturbed. Soon after the snoring
began in the experimental groups, however, the researchers filled
their rooms with the same rose scent. Upon awakening, the subjects
were tested on their knowledge of where the matches had been
discovered on the previous day. Those subjects without the scent
answered correctly 86 percent of the time. Those re-exposed to
the scent answered correctly 97 percent of the time. Brain imaging
experiments showed the direct involvement of the hippocampus.
It is quite possible that the smell enhanced recall during the offline
processing that normally occurs during sleep.
In the highly competitive world of school performance, there are
parents who would die to give their kids an 11 percent edge over the
competition. Some CEOs would appreciate such an advantage, too,
in the face of anxious shareholders.
Sensory branding
Author Judith Viorst once said, “Strength is the capacity to break
a chocolate bar into four pieces, and then eat just one of the pieces.”
She was of course referring to the power of the confection on self-
will. It’s a testament to the power of emotion to incite action.
That’s just what emotions do: affect motivations. As we discussed
in the Attention chapter, emotions are used by the brain to select

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certain inputs for closer inspection. Because smells stimulate areas
in the brain responsible for creating emotions as well as memories, a
number of business people have asked, “Can smell, which can affect
motivation, also affect sales?”
One company tested the effects of smell on business and found a
whopper of a result. Emitting the scent of chocolate from a vending
machine, it found, drove chocolate sales up 60 percent. That’s quite a
motivation. The same company installed a waffle-cone-smell emitter
near a location-challenged ice cream shop (it was inside a large hotel
and hard to find). Sales soared 50 percent, leading the inventor to
coin the term “aroma billboard” to describe the technique.
Welcome to the world of sensory branding. An entire industry is
beginning to pay attention to human sensory responses, with smell as
the centerpiece. In an experiment for a clothing store, investigators
subtly wafted the smell of vanilla in the women’s department, a
scent known to produce a positive response among women. In the
men’s department, they diffused the smell of rose maroc, a spicy,
honeylike fragrance that had been pretested on men. The retail
results were amazing. When the scents were deployed, sales doubled
from their typical average in each department. And when the scents
were reversed—vanilla for men and rose maroc for women—sales
plummeted below their typical average. The conclusion? Smell
works, but only when deployed in a particular way. “You can’t just
use a pleasant scent and expect it to work,” says Eric Spangenberg,
the scientist in charge of the work. “It has to be congruent.” In
recognition of this fact, Starbucks does not allow employees to wear
perfume on company time. It interferes with the seductive smell of
the coffee they serve and its potential to attract customers.
Marketing professionals have begun to come up with recommen-
dations for the use of smell in differentiating a brand: First, match
the scent with the hopes and needs of the target market. The pleas-
ant smell of coffee may remind a busy executive of the comforts of
home, a welcome relief when about to close a deal. Second, integrate

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the odor with the “personality” of the object for sale. The fresh smell
of a forest, or the salty odor of a beach, might evoke a sense of ad-
venture more so than, say, the smell of vanilla, in potential buyers of
SUVs. Remember the Proust effect, that smell can evoke memory.
Smells at work (not coming from the fridge)
What about the role of learning in a business setting? Two
ideas come to mind, based loosely on my teaching experiences. I
occasionally teach a molecular biology class for engineers, and one
time I decided to do my own little Proust experiment. (There was
nothing rigorous about this little parlor investigation; it was simply
an informal inquiry.) Every time I taught one section on an enzyme
(called RNA polymerase II), I prepped the room by squirting the
perfume Brut on one wall. In an identical class in another building,
I taught the same material, but I did not squirt Brut when describing
the enzyme. Then I tested everybody, squirting the perfume into
both classrooms. Every time I did this experiment, I got the same
result. The people who were exposed to the perfume during learning
did better on subject matter pertaining to the enzyme—sometimes
dramatically better—than those who were not.
And that led me to an idea. Many businesses have a need to teach
their clients about their products, from how to implement software to
how to repair airplane engines. For financial reasons, the classes are
often compressed for time and packed with information, 90 percent
of which is forgotten a day later. (For most declarative subjects,
memory degradation starts the first few hours after the teaching is
finished.) But what if the teacher paired a smell with each lesson, as
in my Brut experiment? One might even expose the students to the
smell while they are asleep. The students could not help but associate
the autobiographical experience of the class—complete with the
intense transfer of information—with the odorant.
After the class, the students (let’s say they’re learning to repair
airplane engines) return to their company. Two weeks later, they are

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confronted with a room full of newly broken engines to repair. Most
of them will have forgotten something in the intense class they took
and need to review their notes. This review would take place in the
presence of the smell they encountered during the learning. Would
it give a boost to their memories? What if they were exposed to the
smell while they were in the shop repairing the actual engines? The
enhanced memory might improve performance, even cut down on
errors.
Sound preposterous? Possibly. Indeed, one must be careful to
tease out context-dependent learning (remember those dive suits
from Chapter 5) from true multisensory environments. But it’s a
start toward thinking about learning environments that go beyond
the normal near-addiction to visual and auditory information. It is an
area where much potential research fruit lies—truly a place for brain
scientists, educators and business professionals to work together in a
practical way.

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Summary
Rule #9
Stimulate more of the senses
at the same time.
We absorb information about an event through
•
•
our senses, translate it into electrical signals (some for
sight, others from sound, etc.), disperse those signals
to separate parts of the brain, then reconstruct what
happened, eventually perceiving the event as a whole.
The brain seems to rely partly on past experience in
•
•
deciding how to combine these signals, so two people can
perceive the same event very differently.
Our senses evolved to work together—vision
•
•
influencing hearing, for example—which means that we
learn best if we stimulate several senses at once.
Smells have an unusual power to bring back memories,
•
•
maybe because smell signals bypass the thalamus and
head straight to their destinations, which include that
supervisor of emotions known as the amygdala.
Get more at www.brainrules.net

229. vision
Rule #10
Vision trumps all other senses.

231. we do not see with our eyes. We see with our brains.
The evidence lies with a group of 54 wine
aficionados. Stay with me here. To the untrained
ear, the vocabularies that wine tasters use to describe wine may
seem pretentious, more reminiscent of a psychologist describing a
patient. (“Aggressive complexity, with just a subtle hint of shyness”
is something I once heard at a wine-tasting soirée to which I was
mistakenly invited—and from which, once picked off the floor rolling
with laughter, I was hurriedly escorted out the door).
These words are taken very seriously by the professionals,
however. A specific vocabulary exists for white wines and a
specific vocabulary for red wines, and the two are never supposed
to cross. Given how individually we each perceive any sense, I
have often wondered how objective these tasters actually could
be. So, apparently, did a group of brain researchers in Europe.
They descended upon ground zero of the wine-tasting world, the
University of Bordeaux, and asked: “What if we dropped odorless,

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tasteless red dye into white wines, then gave it to 54 wine-tasting
professionals?” With only visual sense altered, how would the
enologists now describe their wine? Would their delicate palates
see through the ruse, or would their noses be fooled? The answer is
“their noses would be fooled.” When the wine tasters encountered
the altered whites, every one of them employed the vocabulary of the
reds. The visual inputs seemed to trump their other highly trained
senses.
Folks in the scientific community had a field day. Professional
research papers were published with titles like “The Color of Odors”
and “The Nose Smells What the Eye Sees.” That’s about as much
frat boy behavior as prestigious brain journals tolerate, and you can
almost see the wicked gleam in the researchers’ eyes. Data such as
these point to the nuts and bolts of this chapter’s Brain Rule. Visual
processing doesn’t just assist in the perception of our world. It
dominates the perception of our world. Starting with basic biology,
let’s find out why.
a hollywood horde
We see with our brains.
This central finding, after years of study, is deceptively simple.
It is made more misleading because the internal mechanics of
vision seem easy to understand. First, light (groups of photons,
actually) enters our eyes, where it is bent by the cornea, the fluid-
filled structure upon which your contacts normally sit. Then the
light travels through the eye to the lens, where it is focused and
allowed to strike the retina, a group of neurons in the back of the
eye. The collision generates electric signals in these cells, and the
signals travel deep into the brain via the optic nerve. The brain then
interprets the electrical information, and we become visually aware.
These steps seem effortless, 100 percent trustworthy, capable of
providing a completely accurate representation of what’s actually out
there.

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Though we are used to thinking about our vision in such reliable
terms, nothing in that last sentence is true. The process is extremely
complex, seldom provides a completely accurate representation of
our world, and is not 100 percent trustworthy. Many people think
that the brain’s visual system works like a camera, simply collecting
and processing the raw visual data provided by our outside world.
Such analogies mostly describe the function of the eye, however, and
not particularly well. We actually experience our visual environment
as a fully analyzed opinion about what the brain thinks is out there.
We thought that the brain processed information such as color,
texture, motion, depth, and form in discrete areas; higher-level
structures in the brain then gave meaning to these features, and we
suddenly obtained a visual perception. This is very similar to the
steps discussed in the Multisensory chapter: sensing, routing, and
perception, using bottom-up and top-down methods. It is becoming
clearer that we need to amend this notion. We now know that visual
analysis starts surprisingly early on, beginning when light strikes the
retina. In the old days, we thought this collision was a mechanical,
automated process: A photon shocked a retinal nerve cell into
cracking off some electrical signal, which eventually found its
way to the back of our heads. All perceptual heavy lifting was done
afterward, deep in the bowels of the brain. There is strong evidence
that this is not only a simplistic explanation of what goes on. It is a
wrong explanation.
Rather than acting like a passive antenna, the retina appears to
quickly process the electrical patterns before it sends anything off
to Mission Control. Specialized nerve cells deep within the retina
interpret the patterns of photons striking the retina, assemble
the patterns into partial “movies,” and then send these movies off
to the back of our heads. The retina, it seems, is filled with teams
of tiny Martin Scorseses. These movies are called tracks. Tracks are
coherent, though partial, abstractions of specific features of the
visual environment. One track appears to transmit a movie you might

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call Eye Meets Wireframe. It is composed only of outlines, or edges.
Another makes a film you might call Eye Meets Motion, processing
only the movement of an object (and often in a specific direction).
Another makes Eye Meets Shadows. There may be as many as 12 of
these tracks operating simultaneously in the retina, sending off
interpretations of specific features of the visual field. This new view
is quite unexpected. It’s like discovering that the reason your TV gives
you feature films is that your cable is infested by a dozen amateur
independent filmmakers, hard at work creating the feature while you
watch it.
streams of consciousness
These movies now stream out from the optic nerve, one from
each eye, and flood the thalamus, that egg-shaped structure in the
middle of our heads that serves as a central distribution center for
most of our senses. If these streams of visual information can be
likened to a large, flowing river, the thalamus can be likened to the
beginning of a delta. Once it leaves the thalamus, the information
travels along increasingly divided neural streams. Eventually, there
will be thousands of small neural tributaries carrying parts of the
original information to the back of the brain. The information drains
into a large complex region within the occipital lobe called the visual
cortex. Put your hand on the back of your head. Your palm is now
less than a quarter of an inch away from the area of the brain that is
currently allowing you to see this page. It is a quarter of an inch away
from your visual cortex.
The visual cortex is a big piece of neural acreage, and the various
streams flow into specific parcels. There are thousands of lots, and
their functions are almost ridiculously specific. Some parcels respond
only to diagonal lines, and only to specific diagonal lines (one region
responds to a line tilted at 40 degrees, but not to one tilted at 45).
Some process only the color information in a visual signal; others,
only edges; others, only motion.

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Damage to the region responding to motion results in an
extraordinary deficit: the inability to see moving objects as actually
moving. This can be very dangerous, observable in the famous case
of a Swiss woman we’ll call Gerte. In most respects, Gerte’s eyesight
was normal. She could provide the names of objects in her visual
field; recognize people, both familiar and unfamiliar, as human; read
newspapers with ease. But if she looked at a horse galloping across
a field, or a truck roaring down the freeway, she saw no motion.
Instead, she saw a sequence of static, strobe-like snapshots of the
objects. There was no smooth impression of continuous motion,
no effortless perception of instantaneous changes of location.
There was no motion of any kind. Gerte became terrified to cross
the street. Her strobe-like world did not allow her to calculate the
speed or destination of the vehicles. She could not perceive the cars
as moving, let alone moving toward her (though she could readily
identify the offending objects as automobiles, down to make and
license plate). Gerte even said that talking to someone face-to-face
was like speaking on the phone. She could not see the changing facial
expressions associated with normal conversation. She could not see
“changing” at all.
Gerte’s experience shows the modularity of visual processing. But
it is not just motion. Thousands of streams feeding into these regions
allow for the separate processing of individual features. And if that
was the end of the visual story, we might perceive our world with the
unorganized fury of a Picasso painting, a nightmare of fragmented
objects, untethered colors, and strange, unboundaried edges.
But that’s not what happens, because of what takes place next.
At the point where the visual field lies in its most fragmented state,
the brain decides to reassemble the scattered information. Individual
tributaries start recombining, merging, pooling their information,
comparing their findings, and then sending their analysis to
higher brain centers. The centers gather these hopelessly intricate
calculations from many sources and integrate them at an even more

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sophisticated level. Higher and higher they go, eventually collapsing
into two giant streams of processed information. One of these, called
the ventral stream, recognizes what an object is and what color
it possesses. The other, termed the dorsal stream, recognizes the
location of the object in the visual field and whether it is moving.
“Association regions” do the work of integrating the signals. They
associate—or, better to say, reassociate—the balkanized electrical
signals. Then, you see something. So, the process of vision is not as
simple as a camera taking a picture. The process is more complex
and more convoluted than anyone could have imagined. There is no
real scientific agreement about why this disassembly and reassembly
strategy even occurs.
Complex as visual processing is, things are about to get worse.
We generally trust our visual apparati to serve us a faithful, up-to-
the-minute, 100 percent accurate representation of what’s actually
out there. Why do we believe that? Because our brain insists on
helping us create our perceived reality. Two examples explain this
exasperating tendency. One involves people who see miniature
policemen who aren’t there. The other involves the active perception
of camels.
camels and cops
You might inquire whether I had too much to drink if I told
you right now that you were actively hallucinating. But it’s true. At
this very moment, while reading this text, you are perceiving parts
of this page that do not exist. Which means you, my friend, are
hallucinating. I am about to show you that your brain actually likes to
make things up, not 100 percent faithful to what the eyes broadcast
to it.
There is a region in the eye where retinal neurons, carrying visual
information, gather together to begin their journey into deep brain
tissue. That gathering place is called the optic disk. It’s a strange
region, because there are no cells that can perceive sight in the optic

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disk. It is blind in that region—and you are, too. It is called the blind
spot, and each eye has one. Do you ever see two black holes in your
field of view that won’t go away? That’s what you should see. But
your brain plays a trick on you. As the signals are sent to your visual
cortex, the brain detects the presence of the holes and then does an
extraordinary thing. It examines the visual information 360 degrees
around the spot and calculates what is most likely to be there. Then,
like a paint program on a computer, it fills in the spot. The process
is called “filling in,” but it could be called “faking it.” Some believe
that the brain simply ignores the lack of visual information, rather
than calculating what’s missing. Either way, you’re not getting a 100
percent accurate representation.
It should not be surprising that the brain possesses such
independent-minded imaging systems. Proof is as close as last night’s
dream. But just how much of a loose cannon these systems can be is
evidenced in a phenomenon known as the Charles Bonnet Syndrome.
Millions of people suffer from it. Most who have it keep their mouth
shut, however, and perhaps with good reason. People with Charles
Bonnet syndrome see things that aren’t there. It’s like the blind-
spot-fill-in apparatus gone horribly wrong. For some patients with
Charles Bonnet, everyday household objects suddenly pop into
view. For others, unfamiliar people unexpectedly appear next to
them at dinner. Neurologist Vilayanur Ramachandran describes the
case of a woman who suddenly—and delightfully—observed two
tiny policemen scurrying across the floor, guiding an even smaller
criminal to a matchbox-size van. Other patients have reported
angels, goats in overcoats, clowns, Roman chariots, and elves. The
illusions often occur in the evening and are usually quite benign. It is
common among the elderly, especially among those who previously
suffered damage somewhere in their visual pathway. Extraordinarily,
almost all of the patients experiencing the hallucinations know that
they aren’t real. No one really knows why they occur.
This is just one example of the powerful ways brains participate

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in our visual experience. Far from being a camera, the brain is
actively deconstructing the information given to it by the eyes,
pushing it through a series of filters, and then reconstructing what it
thinks it sees. Or what it thinks you should see.
Yet even this is hardly the end of the mystery. Not only do you
perceive things that aren’t there with careless abandon, but exactly
how you construct your false information follows certain rules.
Previous experience plays an important role in what the brain allows
you to see, and the brain’s assumptions play a vital role in our visual
perceptions. We consider these ideas next.
Since ancient times, people have wondered why two eyes give
rise to a single visual perception. If there is a camel in your left eye
and a camel in your right eye, why don’t you perceive two camels?
Here’s an experiment to try that illustrates the problem nicely.
1) Close your left eye, then stretch your left arm in front of you.
2) Raise up the index finger of your left hand, as if you were
pointing to the sky.
3) Keep the arm in this position while you hold your right arm
about six inches in front of your face. Raise your right index finger
like it too was pointing to the sky.
4) With your eye still closed, position your right index finger so
that it appears just to the left of your left index finger.
5) Now speedily open you left eye and close the right one. Do this
several times.
If you positioned your fingers correctly, your right finger will
jump to the other side of your left finger and back again. When you
open both eyes, the jumping will stop. This little experiment shows
that the two images appearing on each retina always differ. It also
shows that both eyes working together somehow give the brain
enough information to see non-jumping reality.
Why do you see only one camel? Why do you see two arms

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with stable, non-jumping fingers? Because the brain interpolates
the information coming from both eyes. It makes about a gazillion
calculations, then provides you its best guess. And it is a guess. You
can actually show that the brain doesn’t really know where things
are. Rather, it hypothesizes the probability of what the current
event should look like and then, taking a leap of faith, approximates
a viewable image. What you experience is not the image. What you
experience is the leap of faith. Why does the brain do this? Because
it is forced to solve a problem: We live in a three-dimensional world,
but the light falls on our retina in a two-dimensional fashion. The
brain must deal with this disparity if it is going to accurately portray
the world. Just to complicate things, our two eyes give the brain two
separate visual fields, and they project their images upside down
and backward. To make sense of it all, the brain is forced to start
guessing.
Upon what does it base its guesses, at least in part? The answer
is bone-chilling: prior experience with events in your past. After
adamantly inserting numerous assumptions about the received
information (some of these assumptions may be inborn), the brain
then offers up its findings for your perusal. It goes to all of this
trouble for an important reason dripping with Darwinian good will:
so you will see one camel in the room when there really is only one
camel in the room (and see its proper depth and shape and size and
even hints about whether or not it will bite you). All of this happens
in about the time it takes to blink your eyes. Indeed, it is happening
right now.
If you think the brain has to devote to vision a lot of its precious
thinking resources, you are right on the money. It takes up about half
of everything you do, in fact. This helps explains why snooty wine
tasters with tons of professional experience throw out their taste
buds so quickly in the thrall of visual stimuli. And that lies at the very
heart of this chapter’s Brain Rule.

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phantom of the ocular
In the land of sensory kingdoms, there are many ways to show
that vision isn’t the benevolent prime minister but the dictatorial
emperor. Take phantom-limb experiences. Sometimes, people who
have suffered an amputation continue to experience the presence
of their limb, even though no limb exists. Sometimes the limb is
perceived as frozen into a fixed position. Sometimes it feels pain.
Scientists have used phantoms to demonstrate the powerful influence
vision has on our senses.
An amputee with a “frozen” phantom arm was seated at a table
upon which had been placed a topless, divided box. There were
two portals in the front, one for the arm and one for the stump.
The divider was a mirror, and the amputee could view a reflection
of either his functioning hand or his stump. When he looked at his
functioning hand, he could see his right arm present and his left
arm missing. But when he looked at the reflection of his right arm
in the mirror—what looked like another arm—the phantom limb on
the other side of the box suddenly “woke up.” If he moved his normal
hand while gazing at its reflection, he could feel his phantom move,
too. And when he stopped moving his right arm, his missing left arm
“stopped” also. The addition of visual information began convincing
his brain of a miraculous rebirth of the absent limb. This is vision
not only as dictator but as faith healer. The visual-capture effect is so
powerful, it can be used to alleviate pain in the phantom.
How do we measure vision’s dominance?
One way is to show its effects on learning and memory.
Researchers historically have used two types of memory in their
investigations. The first, recognition memory, is a glorified way
to explain familiarity. We often deploy recognition memory when
looking at old family photographs, such as gazing at a picture of an
old aunt not remembered for years. You don’t necessarily recall her
name, or the photo, but you still recognize her as your aunt. You may

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not be able to recall certain details, but as soon as you see it, you
know that you have seen it before.
Other types of learning involve the familiar working memory.
Explained in greater detail in the Memory chapters, working memory
is that collection of temporary storage buffers with fixed capacities
and frustratingly short life spans. Visual short-term memory is the
slice of that buffer dedicated to storing visual information. Most of
us can hold about four objects at a time in that buffer, so it’s a pretty
small space. And it appears to be getting smaller. Recent data show
that as the complexity of the objects increases, the number of objects
capable of being captured drops. The evidence also suggests that the
number of objects and complexity of objects are engaged by different
systems in the brain, turning the whole notion of short-term capacity,
if you will forgive me, on its head. These limitations make it all the
more remarkable—or depressing—that vision is probably the best
single tool we have for learning anything.
worth a thousand words
When it comes to memory, researchers have known for more
than 100 years that pictures and text follow very different rules. Put
simply, the more visual the input becomes, the more likely it is to be
recognized—and recalled. The phenomenon is so pervasive, it has
been given its own name: the pictorial superiority effect, or PSE.
Human PSE is truly Olympian. Tests performed years ago
showed that people could remember more than 2,500 pictures with
at least 90 percent accuracy several days post-exposure, even though
subjects saw each picture for about 10 seconds. Accuracy rates a year
later still hovered around 63 percent. In one paper—adorably titled
“Remember Dick and Jane?”—picture recognition information was
reliably retrieved several decades later.
Sprinkled throughout these experiments were comparisons with
other forms of communication. The favorite target was usually text
or oral presentations, and the usual result was “picture demolishes

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them both.” It still does. Text and oral presentations are not just less
efficient than pictures for retaining certain types of information;
they are way less efficient. If information is presented orally, people
remember about 10 percent, tested 72 hours after exposure. That
figure goes up to 65 percent if you add a picture.
The inefficiency of text has received particular attention. One
of the reasons that text is less capable than pictures is that the brain
sees words as lots of tiny pictures. Data clearly show that a word is
unreadable unless the brain can separately identify simple features
in the letters. Instead of words, we see complex little art-museum
masterpieces, with hundreds of features embedded in hundreds of
letters. Like an art junkie, we linger at each feature, rigorously and
independently verifying it before moving to the next. The finding
has broad implications for reading efficiency. Reading creates a
bottleneck. My text chokes you, not because my text is not enough
like pictures but because my text is too much like pictures. To our
cortex, unnervingly, there is no such thing as words.
That’s not necessarily obvious. After all, the brain is as adaptive as
Silly Putty. With years of reading books, writing email, and sending
text messages, you might think the visual system could be trained
to recognize common words without slogging through tedious
additional steps of letter-feature recognition. But that is not what
happens. No matter how experienced a reader you become, you will
still stop and ponder individual textual features as you plow through
these pages, and you will do so until you can’t read anymore.
Perhaps, with hindsight, we could have predicted such
inefficiency. Our evolutionary history was never dominated by text-
filled billboards or Microsoft Word. It was dominated by leaf-filled
trees and saber-toothed tigers. The reason vision means so much to
us may be as simple as the fact that most of the major threats to our
lives in the savannah were apprehended visually. Ditto with most
of our food supplies. Ditto with our perceptions of reproductive
opportunity.

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The tendency is so pervasive that, even when we read, most of
us try to visualize what the text is telling us. “Words are only postage
stamps delivering the object for you to unwrap,” George Bernard
Shaw was fond of saying. These days, there is a lot of brain science
technology to back him up.
a punch in the nose
Here’s a dirty trick you can pull on a baby. It may illustrate
something about your personality. It certainly illustrates something
about visual processing.
Tie a ribbon around the baby’s leg. Tie the other end to a bell.
At first she seems to be randomly moving her limbs. Soon, however,
the infant learns that if she moves one leg, the bell rings. Soon she
is happily—and preferentially—moving that leg. The bell rings and
rings and rings. Now cut the ribbon. The bell no longer rings. Does
that stop the baby? No. She still kicks her leg. Something is wrong,
so she kicks harder. Still no sound. She does a series of rapid kicks
in sequence. Still no success. She gazes up at the bell, even stares at
the bell. This visual behavior tells us she is paying attention to the
problem. Scientists can measure the brain’s attentional state even
with the diaper-and-breast-milk crowd because of this reliance on
visual processing.
This story illustrates something fundamental about how brains
perceive their world. As babies begin to understand cause-and-
effect relationships, we can determine how they pay attention by
watching them stare at their world. The importance of this gazing
behavior cannot be underestimated. Babies use visual cues to show
they are paying attention to something—even though nobody taught
them to do that. The conclusion is that babies come with a variety of
preloaded software devoted to visual processing.
That turns out to be true. Babies display a preference for patterns
with high contrast. They seem to understand the principle of
common fate: Objects that move together are perceived as part of the

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same object, such as stripes on a zebra. They can discriminate human
faces from non-human equivalents and seem to prefer them. They
possess an understanding of size related to distance—that if an object
is getting closer (and therefore getting bigger), it is still the same
object. Babies can even categorize visual objects by common physical
characteristics. The dominance that vision displays behaviorally
begins in the tiny world of infants.
And it shows up in the even tinier world of DNA. Our sense of
smell and color vision are fighting violently for evolutionary control,
for the right to be consulted first whenever something on the
outside happens. And vision is winning. In fact, about 60 percent
of our smell-related genes have been permanently damaged in this
neural arbitrage, and they are marching toward obsolescence at a
rate fourfold faster than any other species sampled. The reason for
this decommissioning is simple: The visual cortex and the olfactory
cortex take up a lot of neural real estate. In the crowded zero-sum
world of the sub-scalp, something has to give.
Whether looking at behavior, cells, or genes, we can observe
how important visual sense is to the human experience. Striding
across our brain like an out-of-control superpower, giant swaths of
biological resource are consumed by it. In return, our visual system
creates movies, generates hallucinations, and consults with previous
information before allowing us to see the outside. It happily bends
the information from other senses to do its bidding and, at least in
the case of smell, seems to be caught in the act of taking it over.
Is there any point in trying to ignore this juggernaut, especially if
you are a parent, educator, or business professional? You don’t have
to go any further than the wine experts of Bordeaux for proof.
ideas
I owe my career choice to Donald Duck. I am not joking. I
even remember the moment he convinced me. I was 8 years old at
the time, and my mother trundled the family off to a showing of

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an amazing 27-minute animated short called Donald in Mathmagic
Land. Using visual imagery, a wicked sense of humor, and the wide-
eyed wonder of an infant, Donald Duck introduced me to math. Got
me excited about it. From geometry to football to playing billiards,
the power and beauty of mathematics were made so real for this
nerd-in-training, I asked if I could see it a second time. My mother
obliged, and the effect was so memorable, it eventually influenced
my career choice. I now have a copy of those valuable 27 minutes in
my own home and regularly inflict it upon my poor children. Donald
in Mathmagic Land won an Academy Award for best animated short
of 1959. It also should have gotten a “Teacher of the Year” award.
The film illustrates—literally—the power of the moving image in
communicating complex information to students. It’s one inspiration
for these suggestions.
Teachers should learn why pictures grab attention
Educators should know how pictures transfer information.
There are things we know about how pictures grab attention that
are rock solid. We pay lots of attention to color. We pay lots of
attention to orientation. We pay lots of attention to size. And we
pay special attention if the object is in motion. Indeed, most of the
things that threatened us in the Serengeti moved, and the brain has
evolved unbelievably sophisticated trip-wires to detect it. We even
have specialized regions to distinguish when our eyes are moving
versus when our world is moving. These regions routinely shut
down perceptions of eye movement in favor of the environmental
movement.
Teachers should use computer animations
Animation captures the importance not only of color and
placement but also of motion. With the advent of web-based
graphics, the days when this knowledge was optional for educators
are probably over. Fortunately, the basics are not hard to learn. With

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today’s software, simple animations can be created by anybody who
knows how to draw a square and a circle. Simple, two-dimensional
pictures are quite adequate; studies show that if the drawings
are too complex or lifelike, they can distract from the transfer of
information.
Test the power of images
Though the pictorial superiority effect is a well-established fact
for certain types of classroom material, it is not well-established
for all material. Data are sparse. Some media are better at
communicating some types of information than others. Do pictures
communicate conceptual ideas such as “freedom” and “amount”
better than, say a narrative? Are language arts better represented in
picture form, or are other media styles more robust? Working out
these issues in real-world classrooms would provide the answer, and
that takes collaboration between teachers and researchers.
Communicate with pictures more than words
“Less text, more pictures” were almost fighting words in 1982.
They were used derisively to greet the arrival of USA Today, a brand-
new type of newspaper with, as you know, less text, more pictures.
Some predicted the style would never work. Others predicted that
if it did, the style would spell the end of Western civilization as the
newspaper-reading public knows it. The jury may be out on the latter
prediction, but the former has a powerful and embarrassing verdict.
Within four years, USA Today had the second highest readership of
any newspaper in the country, and within 10, it was the number one.
It still is.
What happened? First, we know that pictures are a more efficient
delivery mechanism of information than text. Second, the American
work force is consistently overworked, with more things being done
by fewer people. Third, many Americans still read newspapers. In
the helter-skelter world of overworked Americans, more-efficient

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information transfer may be the preferred medium. As the success of
USA Today suggests, the attraction may be strong enough to persuade
consumers to reach for their wallet. So, pictorial information may
be initially more attractive to consumers, in part because it takes
less effort to comprehend. Because it is also a more efficient way to
glue information to a neuron, there may be strong reasons for entire
marketing departments to think seriously about making pictorial
presentations their primary way of transferring information.
The initial effect of pictures on attention has been tested. Using
infrared eye-tracking technology, 3,600 consumers were tested on
1,363 print advertisements. The conclusion? Pictorial information
was superior in capturing attention—independent of its size. Even if
the picture was small and crowded with lots of other non-pictorial
elements close to it, the eye went to the visual. The researchers in
the study, unfortunately, did not check for retention.
Toss your PowerPoint presentations
The presentation software called PowerPoint has become
ubiquitous, from corporate boardrooms to college classrooms to
scientific conferences. What’s wrong with that? It’s text-based,
with six hierarchical levels of chapters and subheads—all words.
Professionals everywhere need to know about the incredible
inefficiency of text-based information and the incredible effects of
images. Then they need to do two things:
1) Burn their current PowerPoint presentations.
2) Make new ones.
Actually, the old ones should be stored, at least temporarily, as
useful comparisons. Business professionals should test their new
designs against the old and determine which ones work better. A
typical PowerPoint business presentation has nearly 40 words per
slide. That means we have a lot of work ahead of us.

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Summary
Rule #10
Vision trumps all other senses.
Vision is by far our most dominant sense, taking up half
•
•
of our brain’s resources.
What we see is only what our brain tells us we see,
•
•
and it’s not 100 percent accurate.
The visual analysis we do has many steps.The retina
•
•
assembles photons into little movie-like streams of
information.The visual cortex processes these streams,
some areas registering motion, others registering color,
etc. Finally, we combine that information back together so
we can see.
We learn and remember best through pictures, not
•
•
through written or spoken words.
Get more at www.brainrules.net

249. gender
Rule #11
Male and female brains are different.

251. the man was a hot dog. The woman was a bitch.
The results of the experiment could be summarized
in those two sentences. Three researchers created a
fictitious assistant vice president of an aircraft company.
Four groups of experimental subjects, with equal numbers of men
and women in each group, were asked to rate this fictional person’s
job performance. Each group was given the vice president’s brief job
description, but the first group also was told that the vice president
was a man. They were asked to rate both the competence and the
likability of the candidate. They gave a very flattering review, rating
the man “very competent” and “likable.” The second group was told
that the vice president was a woman. She was rated “likable” but “not
very competent.” All other factors were equal. Only the perceived
gender had changed.
The third group was told that the vice president was a male
superstar, a stellar performer on the fast track at the company. The
fourth group was told that the vice president was a female superstar,

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also on the express lane to the executive washroom. As before, the
third group rated the man “very competent” and “likable.” The
woman superstar also was rated “very competent.” But she was not
rated “likable.” In fact, the group’s descriptions included words such
as “hostile.” As I said, the man was a hot dog. The woman was a
bitch.
The point is, gender biases hurt real people in real-world
situations. As we hurtle headlong into the controversial world
of brains and genders, keeping these social effects in mind is
excruciatingly important. There is a great deal of confusion regarding
the way men and women relate to each other, and even more about
why. There is confusion about the terms as well, blurring the line
between the concepts of “sex” and “gender.” Here, sex will generally
refer to biology and anatomy. Gender will refer mostly to social
expectations. Sex is set into the concrete of DNA. Gender is not. The
differences between men’s and women’s brains start with how they
got that way in the first place.
the x factor
How do we become male and female? The road to sex assignment
starts out with all the enthusiasm sex usually stimulates. Four
hundred million sperm fall all over themselves attempting to find
one egg during intercourse. The task is not all that difficult. In the
microscopic world of human fertilization, the egg is the size of
the Death Star, and the sperm are the size of X-wing fighters. X is
a good letter for this enterprise—the name of that very important
chromosome that half of all sperm and all eggs carry. You recall
chromosomes from biology class, those writhing strings of DNA
packed into the nucleus that contain the information necessary to
make you. It takes 46 of them to do it, which you can think of as 46
volumes in an encyclopedia. Twenty-three come from Mom, and 23
come from Dad. Two are sex chromosomes. At least one of those
chromosomes has to be an X chromosome, or you will die.

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If you get two X chromosomes, you go into the ladies locker
room all your life; an X and Y puts you forever in the men’s. This sex
assignment is controlled by the male. Henry VIII’s wives wish he’d
known that. He executed one of them for being unable to produce a
boy as heir to the throne, but he should have executed himself. The
Y can be donated only by sperm (the egg never carries one), so the
male determines the sex.
Gender differences can be divided into three areas: genetic,
neuroanatomical, and behavioral. Scientists usually spend their
whole careers exploring only one—each difference is like a separate
island in a common research ocean. We’ll tour all three, starting with
a molecular explanation of why Henry VIII owes Anne Boleyn a big
fat apology.
One of the most interesting facts about the Y chromosome is
that you don’t need most of it to make a male. All it takes to kick-
start the male developmental program is a small snippet near the
middle, carrying a gene called SRY. In our tour, we immediately
notice Gene Island is dominated by a single scientist, David C. Page.
He is the researcher who isolated SRY. Though in his 50s, Page looks
to be about 28 years old. As director of the Whitehead Institute and
a professor at MIT, he is a man of considerable intellect. He also
is charming and has a refreshingly wicked sense of humor. Page is
the world’s first molecular sex therapist. Or, better, sex broker. He
discovered that you can destroy the SRY gene in a male embryo
and get a female, or add SRY to a female embryo and turn her into
a male (SR stands for “sex reversal”). Why can you do this? In a fact
troubling to anybody who believes males are biologically hard-wired
to dominate the planet, researchers discovered that the basic default
setting of the mammalian embryo is to become female.
There is terrible inequality between the two chromosomes. The
X chromosome does most of the heavy developmental lifting, while
the little Y has been shedding its associated genes at a rate of about
five every one million years, committing suicide in slow motion. It’s

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now down to less than 100 genes. By comparison, the X chromosome
carries about 1,500 genes, all necessary participants in embryonic
construction projects. These are not showing any signs of decay.
With only a single X chromosome, males need every X gene they
can get. Females, however, have double the necessary amount. You
can think of it like a cake recipe calling for only one cup of flour. If
you decide to put in two, things will change in a most unpleasant
fashion. The female embryo uses what may be the most time-honored
weapon in the battle of the sexes to solve the problem of two X’s:
She simply ignores one of them. This chromosomal silent treatment
is known as X inactivation. One of the chromosomes is tagged with
the molecular equivalent of a “Do Not Disturb” sign. Since there are
two X’s from which to choose, Mom’s or Dad’s, researchers wanted to
know who preferentially got the sign.
The answer was completely unexpected. There were no
preferences. Some cells in the developing little girl embryo hung
their sign around Mom’s X. Neighboring cells hung their sign around
Dad’s. At this point in research, there doesn’t appear to be any rhyme
or reason, and it is considered a random event. This means that
cells in the female embryo are a complex mosaic of both active and
inactive mom-and-pop X genes. Because males require all 1,500 X
genes to survive, and they have only one X-chromosome, it would
be stupid for them to hang up “Do Not Disturb” notes. They never
do it. X inactivation does not occur in guys. And because males must
get their X from Mom, all men are literally, with respect to their X
chromosome, Momma’s Boys—unisexed. That’s very different from
their sisters, who are more genetically complex. These bombshells
describe our first truly genetic-based findings of potential gender
differences.
We now know the function of many of the 1,500 genes that
reside on the X chromosome. Swallow hard here. Many of those
genes involve brain function. Many of them govern how we think.
In 2005, the human genome was sequenced, and an unusually large

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percentage of the X chromosome genes were found to create proteins
involved in brain manufacture. Some of these genes may be involved
in establishing higher cognitive functions, from verbal skills and
social behavior to certain types of intelligence. Researchers call the X
chromosome a cognitive “hot spot.”
These findings represent one of the most important regions on
Gene Island. But it is hardly the only important region, and not even
the most important island.
is bigger better?
The purpose of genes is to create molecules that mediate the
functions of the cells in which they reside. Collections of these
cells create the neuroanatomy of the brain (which in turn creates
our behavior). Leaving Gene Island, our next stop is Cell Island, a
region where scientists investigate large structures in the brain, or
neuroanatomy. Here, the real trick is finding structures that aren’t
affected by sex chromosome dosage.
Labs—headed by scientists of both sexes, I should perhaps point
out—have found differences in the front and prefrontal cortex,
areas of the brain that control much of our decision-making ability.
This cortex is fatter, in certain parts, in women than in men. There
are sex-based differences in the limbic system, which controls our
emotional life and mediates some types of learning. Prominent
differences lie in the amygdala, controlling not only the generation
of emotions but also the ability to remember them. Running counter
to current social prejudice, this region is much larger in men than
it is in women. At rest, female amygdalas tend to talk mostly to the
left hemisphere, while male amygdalas do most of their chatting with
the right hemisphere. Brain cells communicate via biochemicals,
and these have not escaped sex differences, either. The regulation
of serotonin is particularly dramatic. Serotonin is key in regulating
emotion and mood (Prozac works by altering the regulation of this
neurotransmitter). Males can synthesize serotonin about 52 percent

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faster than females. Do these physical differences mean anything?
In animals, the size of structures is thought to reflect their relative
importance to survival. Human examples at first blush seem to
follow a similar pattern. We already have noticed that violinists
have bigger areas of the brain devoted to controlling their left hand
than their right. But neuroscientists nearly come to blows over how
structure relates to function. We don’t yet know whether differences
in neurotransmitter distributions, or in the size of a brain region,
mean anything substantial.
Such cautions have not stopped brain scientists from going after
the question of behavior differences, and they won’t stop us, either.
Fasten your seat belts and strap on the Kevlar, for we are about to
land on the noisiest, most intellectually violent island on our
imaginary itinerary: Behavior Island.
battle of the sexes
I didn’t really want to write about this. Characterizing gender-
specific behaviors has a long and mostly troubled history. Even
institutions holding our best minds aren’t immune. Larry Summers
was Harvard’s president, for Pete’s sake, when he attributed girls’
lower math and science scores to behavioral genetics, comments
that cost him his job. And he is in exceptionally good intellectual
company. Consider these three quotes:
“The female is an impotent male, incapable of making semen because of
the coldness of her nature. We therefore should look upon the female state
as if it were a deformity, though one that occurs in the ordinary course of
nature.”
Aristotle (384–332 bc)
“Girls begin to talk and to stand on their feet sooner than boys because
weeds always grow up more quickly than good crops.”
Martin Luther (1483–1546)

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“If they can put a man on the moon ... why can’t they put them all there?”
Jill (1985, graffiti on a bathroom wall,
in response to Luther’s quote)
And so the weary battle of the sexes continues. Almost 2,400
years of history separate Aristotle from Jill, yet we seem to have
barely moved. Invoking planet metaphors like Venus and Mars,
some purport to expand perceived differences into prescriptions for
relationships. And this is the most scientifically progressive era in
human history.
Mostly, I think, it comes down to statistics.
There may very well be differences in the way men and women
think about some things. But when people hear about measurable
differences, they often think scientists are talking about individuals,
such as themselves. That’s a big mistake. When scientists look
for behavioral trends, they do not look at individuals. They look at
populations. Statistics in these studies can never apply to individuals.
Trends emerge, but there are variations within a population, often
with significant overlaps between the genders. It is true that every
time neuroscientist Flo Haseltine does an fMRI, she sees different
parts of the brain light up depending upon whether she is viewing
a man or a woman. Exactly how that relates to your behavior is a
completely separate question.
first hints
What we do know about the biological roots of behavioral
differences began with brain pathologies. Mental retardation is more
common in males than in females in the general population. Many
of these pathologies are caused by mutations in any one of 24 genes
within the X chromosome. As you know, males have no backup X. If
their X gets damaged, they have to live with the consequences. If a
female’s X is damaged, she can often ignore the consequences. This
represents to date one of the strongest pieces of evidence showing

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the involvement of X chromosomes in brain function and thus brain
behavior.
Mental health professionals have known for years about sex-based
differences in the type and severity of psychiatric disorders. Males are
more severely afflicted by schizophrenia than females, for example.
By more than 2 to 1, women are more likely to get depressed than
men, a figure that shows up just after puberty and remains stable for
the next 50 years. Males exhibit more antisocial behavior. Females
have more anxiety. Most alcoholics and drug addicts are male. Most
anorexics are female. Says Thomas Insel, from the National Institute
of Mental Health, “It’s pretty difficult to find any single factor that’s
more predictive for some of these disorders than gender.”
But what about normal behavior? The three research islands
have very few bridges between them. There are bridge-construction
projects, however, and we are going to talk about two of the best.
dealing with traumatic situations
It’s a horrible slideshow. In it, a little boy is run over by a car
while walking with his parents. If you ever see that show, you will
never forget it. But what if you could forget it? The brain’s amygdala
aids in the creation of emotions and our ability to remember them.
Suppose there was a magic elixir that could momentarily suppress
it? Such an elixir does exist, and it was used to show that men and
women process emotions differently.
You have probably heard the term left brain vs. right brain.
You may have heard that this underscores creative vs. analytical
people. That’s a folk tale, the equivalent of saying the left side of a
luxury liner is responsible for keeping the ship afloat, and the right
is responsible for making it move through the water. Both sides
are involved in both processes. That doesn’t mean the hemispheres
are equal, however. The right side of the brain tends to remember
the gist of an experience, and the left brain tends to remember the
details.

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Researcher Larry Cahill eavesdropped on men’s and women’s
brains under acute stress (he showed them slasher films), and
what he found is this: Men handled the experience by firing up
the amygdala in their brain’s right hemisphere. Their left was
comparatively silent. Women handled the experience with the
opposite hemisphere. They lit up their left amygdala, their right
comparatively silent. If males are firing up the right hemisphere
(the “gist dictator”), does that mean males remember more gist than
detail of a given emotional experience related to stress? Do females
remember more detail than gist of an emotional experience related
to stress? Cahill decided to find out.
That magic elixir of forgetting, a drug called propranolol,
normally is used to regulate blood pressure. As a beta-blocker, it also
inhibits the biochemistry that usually would activate the amygdala
during emotional experiences. The drug is being investigated as a
potential treatment for combat-related disorders.
But Cahill gave it to his subjects before they watched a traumatic
film. One week later, he tested their memories of it. Sure enough,
the men lost the ability to recall the gist of the story, compared with
men who didn’t take the drug. Women lost the ability to recall the
details. One must be careful not to overinterpret these data. The
results clearly define only emotional responses to stressful situations,
not objective details and summaries. This is not a battle between the
accountants and the visionaries.
Cahill’s results come on the heels of similar findings around the
world. Other labs have extended his work, finding that women recall
more emotional autobiographical events, more rapidly and with
greater intensity, than men do. Women consistently report more
vivid memories for emotionally important events such as a recent
argument, a first date, or a vacation. Other studies show that, under
stress, women tend to focus on nurturing their offspring, while men
tend to withdraw. This tendency in females has sometimes been
called “tend and befriend.” Its origins are unknown, and the reason

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comes straight from the mouth of Stephen Jay Gould: “It is logically,
mathematically, and scientifically impossible to pull them apart.”
This quote reminds me of my two sons in a fight, but Gould is
actually talking about the age-old nature vs. nurture argument.
verbal communication
Behaviorist Deborah Tannen has done some fascinating work
in this area, studying gender differences in verbal capacity. The
Cliff Notes version of Tannen’s and others’ findings over the past
30 years: “Women are better at it.” Though the specifics are often
controversial, much of the empirical support comes from unusual
quarters, including brain pathologies. We have known for years that
language and reading disorders occur approximately twice as often in
little boys as in little girls. Women also recover from stroke-induced
verbal impairment better than men. Many researchers suspect that
risk disparities like these hint at underlying differences in normal
cognition. They often point to neuroanatomical data to explain the
difference: Women tend to use both hemispheres when speaking and
processing verbal information. Men primarily use one. Women tend
to have thick cables connecting their two hemispheres. Men’s are
thinner. It’s as though females have a backup system that is absent in
males.
These clinical data have been used to support findings first
noticed by educators. Girls seem verbally more sophisticated than
little boys as they go through the school system. They are better at
verbal memory tasks, verbal fluency tasks, and speed of articulation.
When these little girls grow up, they are still champions at processing
verbal information. Real as these data seem, however, almost none
of them can be divorced from a social context. That’s why Gould’s
comment is so helpful.
Tannen spent a long time observing and videotaping how little
girls and little boys interact with each other. Her original question
was to find out how boys and girls of different ages talked to their

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best friends, and if any detectable patterns emerged. If she found
some, she wanted to know how stable they were. Would the patterns
detected in childhood also show up in college students? The patterns
she found were predictable and stable, independent of age and
geography. The conversational styles we’ve developed as adults come
directly from the same-sex interactions we solidified as children.
Tannen’s findings center on three areas.
cementing relationships
When girl best friends communicate with each other, they lean
in, maintain eye contact, and do a lot of talking. They use their
sophisticated verbal talents to cement their relationships. Boys
never do this. They rarely face each other directly, preferring either
parallel or oblique angles. They make little eye contact, their gaze
always casting about the room. They do not use verbal information
to cement their relationships. Instead, commotion seems to be
the central currency of a little boy’s social economy. Doing things
physically together is the glue that holds their relationships intact.
My sons, Josh and Noah, have been playing a one-upmanship
game since they were toddlers. A typical version might involve ball
throwing. Josh would say, “I can throw this up to the ceiling,” and
would promptly do so. Then they would laugh. Noah would respond
by grabbing the ball, saying, “Oh yeah? I can throw this up to the
sky,” and throwing the ball higher. This ratcheting, with laughter,
would continue until they reached the “galaxy” or the big prize,
“God.”
Tannen saw this consistent style everywhere she looked—except
when observing little girls. The female version goes something like
this. One sister says, “I can take this ball and throw it to the ceiling,”
and she promptly does. She and her sibling both laugh. The other
sister grabs the ball, throws it up to the ceiling, and says, “I can, too!”
Then they talk about how cool it is that they can both throw the ball
at the same height. This style persists into adulthood for both sexes.

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Tannen’s data, unfortunately, have been misinterpreted as “Boys
always compete, and girls always cooperate.” As this example shows,
however, boys are being extremely cooperative. They are simply
doing it through competition, deploying their favorite strategy of
physical activity.
negotiating status
By elementary school, boys finally start using their verbal skills
for something: to negotiate their status in a large group. Tannen
found that high-status males give orders to the rest of the group,
verbally or even physically pushing the low-status boys around. The
“leaders” maintain their fiefdoms not only by issuing orders but by
making sure the orders are carried out. Other strong members try
to challenge them, so the guys at the top learn quickly to deflect
challenges. This is often done with words as well. The upshot is that
the hierarchy is very evident with boys. And hard. The life of a low-
status male is often miserable. Independent behavior, which is a
characteristic of control at the top, tends to be highly prized.
Tannen found very different behaviors when observing little
girls. There were both high-status and low-status females, as with
the boys. But they used strikingly different strategies to generate and
maintain their hierarchies. The girls spend a lot of time talking. This
communication is so important that the type of talk determines the
status of the relationship. To whom you tell your secrets determines
“best friend” status. The more secrets revealed, the more likely the
girls identify each other as close. Girls tend to de-emphasize the
status between them in these situations. Using their sophisticated
verbal ability, the girls tend not to give top-down imperial orders. If
one of the girls tries issuing commands, the style is usually rejected:
The girl is tagged as “bossy” and isolated socially. Not that decisions
aren’t made. Various members of the group give suggestions, then
discuss alternatives. Eventually, a consensus emerges.
The difference between the genders could be described as the

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addition of a single powerful word. Boys might say, “Do this.” Girls
would say, “Let’s do this.”
into adulthood
Tannen found that over time, these ways of using language
became increasingly reinforced, which incited different social
sensitivities in the two groups. Any boy who gave orders was a leader.
Any girl who gave orders was bossy. By college age, most of these
styles were deeply entrenched. And that’s when the problems became
most noticeable, showing up at work and in marriage.
A 20-something newlywed was on a drive with her girlfriend,
Emily. She became thirsty. “Emily, are you thirsty?” she asked. With
lifelong experience at verbal negotiation, Emily knew what her
friend wanted. “I don’t know. Are you thirsty?” she responded. There
then ensued a small discussion about whether they were both thirsty
enough to stop the car and get water.
A few days later, the woman was driving with her husband. “Are
you thirsty?” she asked. “No, I’m not,” he replied. They actually got
into an argument that day. She was annoyed because she had wanted
to stop; he was annoyed because she wasn’t direct. This type of
conflict would become increasingly familiar as their marriage aged.
Such scenarios can play out in the work force just as easily.
Women who exert “male” leadership styles are in danger of being
perceived as bossy. Men who do the same thing are often praised
as decisive. Tannen’s great contribution was to show that these
stereotypes form very early in our social development, perhaps
assisted by asymmetric verbal development. They transcend
geography, age, and even time. Tannen, who was an English literature
major, sees these tendencies in manuscripts that go back centuries.
nature or nurture?
Tannen’s findings are statistical patterns, not an all-or-none
phenomenon. She has found that many factors affect our language

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patterns. Regional background, individual personality, profession,
social class, age, ethnicity, and birth order all affect how we use
language to negotiate our social ecologies. Boys and girls are treated
differently socially the moment they are born, and they are often
reared in societies filled with centuries of entrenched prejudice. It
would be a miracle if we somehow transcended our experience and
behaved in an egalitarian fashion.
Given the influence of culture on behavior, it is overly simplistic
to invoke a purely biological explanation for Tannen’s observations.
And, given the great influence of brain biology on behavior, it is also
simplistic to invoke a purely social explanation. The real answer to
the nature-or-nurture question is “We don’t know.” That can be
frustrating to hear. Everybody wants to build bridges between these
islands. Cahill, Tannen, and countless others are doing their best to
provide us with the boards and nails. That’s not the same thing as
saying the connections exist, however. Believing that there are strong
associations between genes and cells and behaviors when there are
none is not only wrong but dangerous. Just ask Larry Summers.
ideas
How can we use these data in the real world?
Get the facts straight on emotions
Dealing with the emotional lives of men and women is a big
part of the job for teachers and business professionals. They need to
know:
1) Emotions are useful. They make the brain pay attention.
2) Men and women process certain emotions differently.
3) The differences are a product of complex interactions between
nature and nurture.
Try different gender arrangements in the classroom
My son’s third-grade teacher began seeing a stereotype that

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worsened as the year progressed. The girls were excelling in the
language arts, and the boys were pulling ahead in math and science.
This was only the third grade! The language-arts differences made
some sense to her. But she knew there was no statistical support
for the contention that men have a better aptitude for math and
science than women. Why, for heaven’s sake, was she presiding over
a stereotype?
The teacher guessed that part of the answer lay in the students’
social participation during class. When the teacher asked a question
of the class, who answered first turned out to be unbelievably
important. In the language arts, the girls invariably answered first.
Other girls reacted with that participatory, “me too” instinct. The
reaction on the part of the boys was hierarchical. The girls usually
knew the answers, the boys usually did not, and the males responded
by doing what low-status males tend to do: They withdrew. A
performance gap quickly emerged. In math and science, boys and
girls were equally likely to answer a question first. But the boys
used their familiar “top each other” conversational styles when they
participated, attempting to establish a hierarchy based on knowledge
aptitude. This included drubbing anyone who didn’t make the
top, including the girls. Bewildered, the girls began withdrawing
from participating in the subjects. Once again, a performance gap
emerged.
The teacher called a meeting of the girls and verified her
observations. Then she asked for a consensus about what they should
do. The girls decided that they wanted to learn math and science
separately from the boys. Previously a strong advocate for mixed-
gender classes, the teacher wondered aloud if that made any sense.
Yet if the girls started losing the math-and-science battle in the
third grade, the teacher reasoned they were not likely to excel in
the coming years. She obliged. It took only two weeks to close the
performance gap.
Can the teacher’s result be applied to classrooms all over the

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world? Actually, the experiment is not a result at all. It is a comment.
This is not a battle that can be won by testing one classroom in a
single school year. This is a battle properly fought by testing hundreds
of classrooms and thousands of students from all walks of life, over a
period of years.
Use gender teams in the workplace
One day, I spoke about gender with a group of executives-in-
training at the Boeing Leadership Center in St. Louis. After showing
some of Larry Cahill’s data about gist and detail, I said, “Sometimes
women are accused of being more emotional than men, from the
home to the workplace. I think that women might not be any more
emotional than anyone else.” I explained that because women
perceive their emotional landscape with more data points (that’s the
detail) and see it in greater resolution, women may simply have more
information to which they are capable of reacting. If men perceived
the same number of data points, they might have the same number
of reactions. Two women in the back began crying softly. After
the lecture, I asked them about their reactions, fearing I may have
offended them. What they said instead blew me away. “It was the
first time in my professional life,” one of them said, “that I didn’t feel
like I had to apologize for who I was.”
And that got me to thinking. In our evolutionary history, having
a team that could simultaneously understand the gist and details
of a given stressful situation helped us conquer the world. Why
would the world of business be exempted from that advantage?
Having an executive team or work group capable of simultaneously
understanding both the emotional forests and the trees of a stressful
project, such as a merger, might be a marriage made in business
heaven. It could even affect the bottom line.
Companies often conduct management training with situation
simulations. They could take a mixed-gendered team and a unisex
team and have them go at a project together. Take another set of

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two teams, but first teach them about the known gender-based
differences before taking on the same project. You have four
potential outcomes. Would the mixed teams do better than the
mono teams? Would the trained groups do better than the untrained
groups? Would these results be stable in, say, six months? You might
find that management teams with a gist/detail balance create the best
shot for productivity. At the very least, this means that both men and
women have an equal right to be at the decision-making table.
We could have environments where gender differences are both
noted and celebrated, as opposed to ignored and marginalized. Had
this been done earlier, we might have more women in science and
engineering now. We might have shattered the archetypal glass
ceiling and saved companies a lot of money. Heck, it may even have
salvaged the Harvard president’s job.

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Summary
Rule #11
Male and female brains are different.
The X chromosome that males have one of and
•
•
females have two of—though one acts as a backup—is
a cognitive “hot spot,” carrying an unusually large
percentage of genes involved in brain manufacture.
Women are genetically more complex, because the
•
•
active X chromosomes in their cells are a mix of Mom’s
and Dad’s. Men’s X chromosomes all come from Mom,
and theirY chromosome carries less than 100 genes,
compared with about 1,500 for the X chromosome.
Men’s and women’s brains are different structurally and
•
•
biochemically—men have a bigger amygdala and produce
serotonin faster, for example—but we don’t know if those
differences have significance.
Men and women respond differently to acute stress:
•
•
Women activate the left hemisphere’s amygdala and
remember the emotional details. Men use the right
amygdala and get the gist.
Get more at www.brainrules.net

269. exploration
Rule #12
We are powerful and natural explorers.

271. my dear son josh got a painful bee sting at the tender age
of 2, and he almost deserved it.
It was a warm, sunny afternoon. We were playing the
“pointing game,” a simple exercise where he would point at
something, and I would look. Then we’d both laugh. Josh had been
told not to touch bumblebees because they could sting him; we used
the word “danger” whenever he approached one. There, in a patch of
clover, he spotted a big, furry, buzzing temptress. As he reached for
it, I calmly said, “Danger,” and he obediently withdrew his hand. He
pointed at a distant bush, continuing our game.
As I looked toward the bush, I suddenly heard a 110-decibel yelp.
While I was looking away, Josh reached for the bee, which promptly
stung him. Josh had used the pointing game as a diversion, and I was
outwitted by a 2-year-old.
“DANGER!” he sobbed as I held him close.
“Danger,” I repeated sadly, hugging him, getting some ice, and
wondering what puberty would be like in 10 years or so.

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This incident was Dad’s inauguration into a behavioral suite
often called the terrible twos. It was a rough baptism for me and
the little guy. Yet it also made me smile. The mental faculties kids
use to distract their dads are the same they will use as grownups
to discover the composition of distant suns or the next alternative
energy. We are natural explorers, even if the habit sometimes stings
us. The tendency is so strong, it is capable of turning us into lifelong
learners. But you can see it best in our youngest citizens (often when
they seem at their worst).
breaking stuff
Babies give researchers a clear view, unobstructed by years
of contaminating experiences, of how humans naturally acquire
information. Preloaded with lots of information-processing software,
infants acquire information using surprisingly specific strategies,
many of which are preserved into adulthood. In part, understanding
how humans learn at this age means understanding how humans
learn at any age.
We didn’t always think that way. If you had said something about
preset brain wiring to researchers 40 years ago, their response would
have been an indignant, “What are you smoking?” or, less politely,
“Get out of my laboratory.” This is because researchers for decades
thought that babies were a blank slate—a tabula rasa. They thought
that everything a baby knew was learned by interactions with its
environments, primarily with adults. This perspective undoubtedly
was formulated by overworked scientists who never had any
children. We know better now. Amazing strides have been made in
understanding the cognitive world of the infant. Indeed, the research
world now looks to babies to show how humans, including adults,
think about practically everything.
Let’s look under the hood of an infant’s mind at the engine that
drives its thinking processes and the motivating fuel that keeps its
intellect running.

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This fuel consists of a clear, high-octane, unquenchable need to
know. Babies are born with a deep desire to understand the world
around them and an incessant curiosity that compels them to
aggressively explore it. This need for explanation is so powerfully
stitched into their experience that some scientists describe it as a
drive, just as hunger and thirst and sex are drives.
Babies seem preoccupied by the physical properties of objects.
Babies younger than a year old will systematically analyze an object
with every sensory weapon at their disposal. They will feel it, kick it,
try to tear it apart, stick it in their ear, stick it in their mouth, give it
to you so you can stick it in your mouth. They appear to be intensely
gathering information about the properties of the object. Babies
methodically do experiments on the objects to see what else they will
do. In our household, this usually meant breaking stuff.
These object-oriented research projects grow increasingly
sophisticated. In one famous set of experiments, babies were
given a rake and a toy set far apart from each other. The babies
quickly learned to use the rake to get the toy. This is not exactly
a groundbreaking discovery, as every parent knows. Then the
researchers observed an astonishing thing. After a few successful
attempts, the babies lost interest in the toy. But not in the
experiment. They would take the toy and move it to different places,
then use the rake to grab it. They even placed the toy out of reach to
see what the rake could do. The toy didn’t seem to matter to them at
all. What mattered was the fact that the rake could move it closer.
They were experimenting with the relationship between objects,
specifically with how one object could influence the other.
Hypothesis testing like that is the way all babies gather
information. They use a series of increasingly self-corrected ideas to
figure out how the world works. They actively test their environment,
much as a scientist would: Make a sensory observation, form a
hypothesis about what is going on, design an experiment capable of
testing the hypothesis, and then draw conclusions from the findings.

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tongue testing
In 1979, Andy Meltzoff rocked the world of infant psychology
by sticking out his tongue at a newborn and being polite enough to
wait for a reply. What he found astonished him. The baby stuck her
tongue back out at him! He reliably measured this imitative behavior
with infants only 42 minutes old. The baby had never seen a tongue
before, not Meltzoff’s and not her own, yet the baby knew she had a
tongue, knew Meltzoff had a tongue, and somehow intuited the idea
of mirroring. Further, the baby knew that if she stimulated a series
of nerves in a certain sequence, she could also stick her tongue out
(definitely not consistent with the notion of tabula rasa).
I tried this with my son Noah. He and I started our relationship
in life by sticking our tongues out at each other. In his first 30
minutes of life, we had struck up an imitative conversation. By the
end of his first week, we were well entrenched in dialogue: Every
time I came into his crib room, we greeted each other with tongue
protrusions. It was purely adaptive on his part, even as it was purely
delightful on my part. If I had not stuck my tongue out initially, he
would not be doing so with such predictability every time I came into
his visual range.
Three months later, my wife picked me up after a lecture at a
medical school, Noah in tow. I was still fielding questions, but I
scooped up Noah and held him close while answering. Out of the
corner of my eye, I noticed Noah gazing at me expectantly, flicking
his tongue out about every five seconds. I smiled and stuck my
tongue out at Noah mid-question. Immediately he squealed and
started sticking his tongue out with abandon, every half-second or so.
I knew exactly what he was doing. Noah made an observation (Dad
and I stick our tongues out at each other), formed a hypothesis (I
bet if I stick my tongue out at Dad, he will stick his tongue back out
at me), created and executed his experiment (I will stick my tongue
out at Dad), and changed his behavior as a result of the evaluation

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of his research (sticking his tongue out more frequently). Nobody
taught Noah, or any other baby, how to do this. And it is a lifelong
strategy. You probably did it this morning when you couldn’t find
your glasses, hypothesized they were in the laundry room, and went
downstairs to look. From a brain science perspective, we don’t even
have a good metaphor to describe how you know to do that. It is so
automatic, you probably had no idea you were looking at the results
of a successful experiment when you found your spectacles lying on
the dryer.
Noah’s story is just one example of how babies use their precious
preloaded information-gathering strategies to gain knowledge they
didn’t have at birth. We also can see it in disappearing cups and
temper tantrums.
Little Emily, before 18 months of age, still believes that if an
object is hidden from view, that object has disappeared. She does not
have what is known as “object permanence.” That is about to change.
Emily has been playing with a washcloth and a cup. She covers the
cup with the cloth, and then pauses for a second, a concerned look
on her brow. Slowly she pulls the cloth away from the cup. The cup
is still there! She glares for a moment, then quickly covers it back
up. Thirty seconds go by before her hand tentatively reaches for the
cloth. Repeating the experiment, she slowly removes the cloth. The
cup is still there! She squeals with delight. Now things go quickly. She
covers and uncovers the cup again and again, laughing loudly each
time. It is dawning on Emily that the cup has object permanence:
Even if removed from view, it has not disappeared. She will repeat
this experiment for more than half an hour. If you have ever spent
time with an 18-month old, you know that getting one to concentrate
on anything for 30 minutes is some kind of miracle. Yet it happens,
and to babies at this age all over the world.
Though this may sound like a delightful form of peek-a-boo, it is
actually an experiment whose failure would have lethal evolutionary
consequences. Object permanence is an important concept to have if

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you live in the savannah. Saber-toothed tigers still exist, for example,
even if they suddenly duck down in the tall grass. Those who didn’t
acquire this knowledge usually were on some predator’s menu.
testing you, too
The distance between 14 months of age and 18 months of age is
extraordinary. This is when children begin to learn that people have
desires and preferences separate from their own. They don’t start out
that way. They think that because they like something, the whole
world likes the same thing. This may be the origin of the “Toddler’s
Creed,” or what I like to call “Seven Rules of Management from a
Baby’s Perspective”:
If I want it, it is mine.
If I give it to you and change my mind later, it is mine.
If I can take it away from you, it is mine.
If we are building something together, all of the pieces are mine.
If it looks just like mine, it is mine.
If it is mine, it will never belong to anybody else, no matter what.
If it is yours, it is mine.
At 18 months, it dawns on babies that this viewpoint may
not always be accurate. They begin to learn that adage that most
newlyweds have to relearn in spades: “What is obvious to you is
obvious to you.”
How do babies react to such new information? By testing it, as
usual. Before the age of 2, babies do plenty of things parents would
rather them not do. But after the age of 2, small children will do
things because their parents don’t want them to. The compliant
little darlings seem to transform into rebellious little tyrants. Many
parents think their children are actively defying them at this
stage. (The thought certainly crossed my mind as I nursed Joshua’s
unfortunate bee sting.) That would be a mistake, however. This stage

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is simply the natural extension of a sophisticated research program
begun at birth.
You push the boundaries of people’s preferences, then stand back
and see how they react. Then you repeat the experiment, pushing
them to their limits over and over again to see how stable the
findings are, as if you were playing peek-a-boo. Slowly you begin to
perceive the length and height and breadth of people’s desires, and
how they differ from yours. Then, just to be sure the boundaries are
still in place, you occasionally do the whole experiment over again.
Babies may not have a whole lot of understanding about their
world, but they know a whole lot about how to get it. It reminds me
of the old Chinese proverb “Catch me a fish and I eat for a day; teach
me to fish and I eat for a lifetime.”
monkey see, monkey do
Why does a baby stick its tongue back out at you? The beginnings
of a neural road map have been drawn in the past few years, at least
for some of the “simpler” thinking behaviors, such as imitation.
Three investigators at the University of Parma were studying the
macaque, assessing brain activity as it reached for different objects in
the laboratory. The researchers recorded the pattern of neural firing
when the monkey picked up a raisin. One day, researcher Leonardo
Fogassi walked into the laboratory and casually plucked a raisin from
a bowl. Suddenly, the monkey’s brain began to fire excitedly. The
recordings were in the raisin-specific pattern, as if the animal had just
picked up the raisin. But the monkey had not picked up the raisin. It
simply saw Fogassi do it.
The astonished researchers quickly replicated and extended their
findings, and then published them in a series of landmark papers
describing the existence of “mirror neurons.” Mirror neurons are
cells whose activity reflect their surroundings. Cues that could elicit
mirror neural responses were found to be remarkably subtle. If a
primate simply heard the sound of someone doing something it had

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previously experienced—say, tearing a piece of paper—these neurons
could fire as if the monkey were experiencing the full stimulus. It
wasn’t long before researchers identified human mirror neurons.
These neurons are scattered across the brain, and a subset is involved
in action recognition—that classic imitative behavior such as babies
sticking out their tongues. Other neurons mirror a variety of motor
behaviors.
We also are beginning to understand which regions of the brain
are involved in our ability to learn from a series of increasingly
self-corrected ideas. We use our right prefrontal cortex to predict
error and to retrospectively evaluate input for errors. The anterior
cingulate cortex, just south of the prefrontal cortex, signals us when
perceived unfavorable circumstances call for a change in behavior.
Every year, the brain reveals more and more of its secrets, with babies
leading the way.
a lifetime journey
We do not outgrow the thirst for knowledge, a fact brought home
to me as a post-doc at the University of Washington. In 1992, Edmond
Fischer shared with Edwin Krebs the Nobel Prize in Physiology
or Medicine. I had the good fortune to be familiar with both their
work and their offices. They were just down the hall from mine.
By the time I arrived, they were already in their mid-70s. The first
thing I noticed upon meeting them was that they were not retired.
Not physically and not mentally. Long after they had earned the right
to be put out to scientific pasture, both had powerful, productive
laboratories in full swing. Every day I would see them walking
down the hall, oblivious to others, chatting about some new finding,
swapping each other’s journals, listening intently to each other’s
ideas. Sometimes they would have someone else along, grilling them
and in turn being grilled about some experimental result. They were
creative like artists, wise as Solomon, lively as children. They had lost
nothing. Their intellectual engines were still revving, and curiosity

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remained the fuel. That’s because our learning abilities don’t have to
change as we age. We can remain lifelong learners.
There may have been strong evolutionary pressure for
maintaining these strategies. Problem-solving was greatly favored
in the unstable environment of the Serengeti. But not just any kind
of problem-solving. When we came down from the trees to the
savannah, we did not say to ourselves, “Good lord, give me a book
and a lecture and a board of directors so I can spend 10 years learning
how to survive in this place.” Our survival did not depend upon
exposing ourselves to organized, pre-planned packets of information.
Our survival depended upon chaotic, reactive information-gathering
experiences. That’s why one of our best attributes is the ability to
learn through a series of increasingly self-corrected ideas. “The red
snake with the white stripe bit me yesterday, and I almost died,” is
an observation we readily made. Then we went a step further: “I
hypothesize that if I encounter the same snake, the same thing will
happen!” It is a scientific learning style we have explored literally for
millions of years. It is not possible to outgrow it in the whisper-short
seven to eight decades we have on the planet.
Researchers have shown that some regions of the adult brain
stay as malleable as a baby’s brain, so we can grow new connections,
strengthen existing connections, and even create new neurons,
allowing all of us to be lifelong learners. We didn’t always think that.
Until five or six years ago, the prevailing notion was that we were
born with all of the brain cells we were ever going to get, and they
steadily eroded in a depressing journey through adulthood to old age.
We do lose synaptic connections with age (some estimates of neural
loss alone are close to 30,000 neurons per day). But the adult brain
also continues creating neurons within the regions normally involved
in learning. These new neurons show the same plasticity as those
of newborns. The adult brain throughout life retains the ability to
change its structure and function in response to experience.
Can we continue to explore our world as we age? I can almost

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hear Krebs and Fischer saying, “Well, duh. Next question.” Of course,
we don’t always find ourselves in environments that encourage such
curiosity as we grow older. I’ve been fortunate to have a career that
allowed me the freedom to pick my own projects. Before that, I was
lucky to have my mother.
from dinosaurs to atheism
I remember, when I was 3 years old, obtaining a sudden interest
in dinosaurs. I had no idea that my mother had been waiting for it.
That very day, the house began its transformation into all things
Jurassic. And Triassic. And Cretaceous. Pictures of dinosaurs would
go up on the wall. I would begin to find books about dinosaurs
strewn on the floor and sofas. Mom would even couch dinner as
“dinosaur food,” and we would spend hours laughing our heads off
trying to make dinosaur sounds. And then, suddenly, I would lose
interest in dinosaurs, because some friend at school acquired an
interest in spaceships and rockets and galaxies. Extraordinarily, my
mother was waiting. Just as quickly as my whim changed, the house
would begin its transformation from big dinosaurs to Big Bang. The
reptilian posters came down, and in their places, planets would begin
to hang from the walls. I would find little pictures of satellites in the
bathroom. Mom even got “space coins” from bags of potato chips,
and I eventually gathered all of them into a collector’s book.
This happened over and over again in my childhood. I got an
interest in Greek mythology, and she transformed the house into
Mount Olympus. My interests careened into geometry, and the house
became Euclidean, then cubist. Rocks, airplanes. By the time I was 8
or 9, I was creating my own house transformations.
One day, around age 14, I declared to my mother that I was an
atheist. She was a devoutly religious person, and I thought this
announcement would crush her. Instead, she said something like
“That’s nice, dear,” as if I had just declared I no longer liked nachos.
The next day, she sat me down by the kitchen table, a wrapped

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package in her lap. She said calmly, “So, I hear you are now an
atheist. Is that true?” I nodded yes, and she smiled. She placed the
package in my hands. “The man’s name is Friedrich Nietzsche, and
the book is called Twilight of the Idols,” she said. “If you are going to
be an atheist, be the best one out there. Bon appetit!”
I was stunned. But I understood a powerful message: Curiosity
itself was the most important thing. And what I was interested in
mattered. I have never been able to turn off this fire hose of curiosity.
Most developmental psychologists believe that a child’s need to
know is a drive as pure as a diamond and as distracting as chocolate.
Even though there is no agreed-upon definition of curiosity in
cognitive neuroscience, I couldn’t agree more. I firmly believe that if
children are allowed to remain curious, they will continue to deploy
their natural tendencies to discover and explore until they are 101.
This is something my mother seemed to know instinctively.
For little ones, discovery brings joy. Like an addictive drug,
exploration creates the need for more discovery so that more joy can
be experienced. It is a straight-up reward system that, if allowed to
flourish, will continue into the school years. As children get older,
they find that learning not only brings them joy, but it also brings
them mastery. Expertise in specific subjects breeds the confidence
to take intellectual risks. If these kids don’t end up in the emergency
room, they may end up with a Nobel Prize.
I believe it is possible to break this cycle, anesthetizing both the
process and the child. By first grade, for example, children learn
that education means an A. They begin to understand that they can
acquire knowledge not because it is interesting, but because it can
get them something. Fascination can become secondary to “What
do I need to know to get the grade?” But I also believe the curiosity
instinct is so powerful that some people overcome society’s message
to go to sleep intellectually, and they flourish anyway.
My grandfather was one of those people. He was born in 1892
and lived to be 101 years old. He spoke eight languages, went through

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several fortunes, and remained in his own house (mowing his own
lawn) until the age of 100, lively as a firecracker to the end. At a party
celebrating his centenary, he took me aside. “You know, Juanito,” he
said, clearing his throat, “sixty-six years separate the Wright brothers’
airplane from Neil Armstrong and the moon.” He shook his head,
marveling. “I was born with the horse and buggy. I die with the space
shuttle. What kind of thing is that?” His eyes twinkled. “I live the
good life!”
He died a year later.
I think of him a lot when I think of exploration. I think of my
mother and her magically transforming rooms. I think of my
youngest son experimenting with his tongue, and my oldest son’s
overwhelming urge to take on a bee sting. And I think that we must
do a better job of encouraging lifelong curiosity, in our workplaces
and especially in our schools.
ideas
Google takes to heart the power of exploration. For 20 percent
of their time, employees may go where their mind asks them to go.
The proof is in the bottom line: Fully 50 percent of new products,
including Gmail and Google News, came from “20 percent time.”
How would we implement such freedom in classrooms? Some people
have tried to harness our natural exploratory tendencies by using
“problem-based” or “discovery-based” learning models. These models
have both strong advocates and strong detractors. Most agree that
these debates are missing hard-nosed empirical results that show the
long-term effects of these styles. I would go further and argue that
what is missing is a real live laboratory in which brain scientists and
education scientists could carry out investigations on a routine, long-
term basis. I would like to describe the place for such research.
Analyze the success of medical schools
In the early 20th
century, John Dewey created a laboratory school

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at the University of Chicago, in part because he thought that learning
should be tested in real-world situations. Though such schools fell
out of favor in the mid-’60s, perhaps with good reason, a 21st
-century
version might look to one of the most successful educational models
out there, a medical school. As William H. Payne, a colleague of
Dewey’s, said, “Psychology, in fact, stands in the same relation to
teaching that anatomy does to medicine.” It still does, though I would
replace “psychology” with “brain science.”
The best medical-school model has three components: a teaching
hospital; faculty who work in the field as well as teach; and research
laboratories. It is a surprisingly successful way of treating people. It
is also a surprisingly successful way to transfer complex information
from one brain to another. I often have watched bright non-science
majors become accepted into a medical-school program and then,
within four years, transform into gifted healers and terrific scientists.
Why do you get good health and good training at the same time?
I am convinced that it is the structure.
1) Consistent exposure to the real world
By combining traditional book-learning and a teaching hospital,
the student gets an unobstructed view of what they are getting into
while they are going through it. Most medical students stroll through
a working hospital on their way to class every day of their training
lives. They confront on a regular basis the very reason they chose
medical school in the first place. By the third year, most students
are in class only half of the time. They spend the other half learning
on the job in the teaching hospital or a clinic associated with it.
Residencies come next for more real-world experience.
2) Consistent exposure to people who operate in the real world
Medical students are taught by people who actually do what they
teach as their “day job.” In more recent years, these people are not
only practicing medical doctors, but practicing medical researchers

284. BRAIN RULES
276
involved in cutting-edge projects with powerful clinical implications.
Medical students are asked to participate.
3) Consistent exposure to practical research programs
Here’s a typical experience: The clinician-professor is lecturing
in a traditional classroom setting and brings in a patient to illustrate
some of his points. The professor announces: “Here is the patient.
Notice that he has disease X with symptoms A, B, C, and D.” He
then begins to lecture on the biology of disease X. While everybody
is taking notes, a smart medical student raises her hand and says, “I
see symptoms A, B, and C. What about symptoms E, F, and G?” The
professor looks a bit chagrined (or excited) and responds, “We don’t
know about symptoms E, F, and G.” You can hear a pin drop at those
moments, and the impatient voices whispering inside the students’
heads are almost audible: “Well, let’s find out!” These are the opening
words of most of the great research ideas in human medicine.
That’s true exploratory magic. By simple juxtaposition of real-
world needs with traditional book learning, a research program is
born. The tendency is so strong that you have to deliberately cut off
the discussions to keep the ideas from forming. Most programs have
chosen not to cut off such discussions. As a result, most American
medical schools possess powerful research wings.
This model gives students a rich view of the field of medicine.
Not only are they taught by people who are involved in the day-to-
day aspect of healing, but they are exposed to people who are trained
to think about the future of medicine. These scientists represent the
brightest minds in the country. And this model provides the single
most natural harness for the exploratory instincts of the human
species I have ever encountered.
Create a college of education that studies the brain
I envision a college of education where the program is all about

285. 12. EXPLORATION
277
brain development. It is divided into three parts, like a medical
school. It has traditional classrooms. It is a community school staffed
and run by three types of faculty: traditional education faculty,
certified teachers who teach the little ones, and brain scientists.
This last group teaches in research labs devoted to a single purpose:
investigating how the human brain learns in teaching environments,
then actively testing hypothesized ideas in real-world classroom
situations.
Students would get a Bachelor of Science in education. The future
educator is infused with deep knowledge about how the human brain
acquires information. Topics range from structural brain anatomy
to psychology, from molecular biology to the latest in cognitive
neuroscience. But the coursework is only the beginning. After their
first year of study, students would start actively participating in the
life of the onsite school.
One semester might be devoted to understanding the
development of the teenage brain. The internship would involve
assisting in a junior high and high school. Another semester might
be devoted to behavioral pathologies such as attention deficit
hyperactivity disorder, and students would assist in a special-
education class. Still another course would be devoted to the effects
of family life on human learning, with students attending parent
association meetings and observing parent-teacher conferences. In
this two-way interaction, the insights of researchers and the insights
of practitioners have a chance to marinate in a single ongoing
intellectual environment. The model creates a vigorous, use-driven
strategic research-and-development program. The practitioner is
elevated to the role of colleague, an active partner in helping shape
the research direction, even as the researcher helps the practitioner
form the specifics of the effort.
This model honors our evolutionary need to explore. It creates
teachers who know about brain development. And it’s a place to do
the real-world research so sorely needed to figure out how, exactly,

286. BRAIN RULES
278
the rules of the brain should be applied to our lives. The model could
be imported to other academic subjects as well. A business school
teaching how to run a small business might actually run one, for
example, as a part of its academic life.
the sense of wonder
If you could step back in time to one of the first real Western-
style universities, say, the University of Bologna, and visit its
biology labs, you would laugh out loud. I would join you. By today’s
standards, biological science in the 11th
century was a joke, a strange
mix of astrological influences, religious forces, dead animals, and
rudely smelling chemical concoctions, some of which were toxic.
But if you went down the hall and peered inside Bologna’s
standard lecture room, you wouldn’t feel as if you were in a museum.
You would feel at home. There is a lectern for the teacher to hold
forth, surrounded by chairs where students absorb whatever is being
held forth. Minus perhaps an overhead or two, it looks remarkably
similar to today’s classrooms. Could it be time for a change?
My sons most likely would say yes. They and my mother are
probably the greatest teachers I ever had.
My 2-year-old son Noah and I were walking down the street
on our way to preschool when he suddenly noticed a shiny pebble
embedded in the concrete. Stopping midstride, the little guy
considered it for a second, found it thoroughly delightful, and let
out a laugh. He spied a small plant an inch farther, a weed valiantly
struggling through a crack in the asphalt. He touched it gently, then
laughed again. Noah noticed beyond it a platoon of ants marching
in single file, which he bent down to examine closely. They were
carrying a dead bug, and Noah clapped his hands in wonder. There
were dust particles, a rusted screw, a shiny spot of oil. Fifteen
minutes had passed, and we had gone only 20 feet. I tried to get
him to move along, having the audacity to act like an adult with a
schedule. He was having none of it. And I stopped, watching my

287. 12. EXPLORATION
279
little teacher, wondering how long it had been since I had taken 15
minutes to walk 20 feet.
The greatest Brain Rule of all is something I cannot prove or
characterize, but I believe in it with all my heart. As my son was
trying to tell me, it is the importance of curiosity.
For his sake and ours, I wish classrooms and businesses were
designed with the brain in mind. If we started over, curiosity would
be the most vital part of both demolition crew and reconstruction
crew. As I hope to have related here, I am very much in favor of both.
I will never forget the moment this little professor taught his
daddy about what it meant to be a student. I was thankful and a little
embarrassed. After 47 years, I was finally learning how to walk down
the street.

288. BRAIN RULES
280
Summary
Rule #12
We are powerful
and natural explorers.
Babies are the model of how we learn—not by passive
•
•
reaction to the environment but by active testing through
observation, hypothesis, experiment, and conclusion.
Specific parts of the brain allow this scientific approach.
•
•
The right prefrontal cortex looks for errors in our
hypothesis (“The saber-toothed tiger is not harmless”),
and an adjoining region tells us to change behavior
(“Run!”).
We can recognize and imitate behavior because of
•
•
“mirror neurons” scattered across the brain.
Some parts of our adult brains stay as malleable as a
•
•
baby’s, so we can create neurons and learn new things
throughout our lives.
Get more at www.brainrules.net

289. Extensive, notated references
and illustrations are online
at www.brainrules.net
references

291. 283
in a list of just about anything, items at the beginning and end are
the easiest for the brain to retrieve. It’s called Serial Position Effect,
and I mention it because I am about to list some of the many people
who helped bring this project to fruition. There obviously will be
a first person and a last person and lots of people in between. This
is not because I see these folks in a hierarchy of values; it is simply
because written languages are necessarily, cursedly linear. Please pay
attention, dear reader, to the folks in the middle as well as to those at
the end points. As I have often mentioned to graduate students, there
is great value in the middle of most U-shaped curves.
First, I thank my publisher at Pear Press, Mark Pearson, the
guiding hand of this project and easily the wisest, oldest young man
with whom I have ever had the joy to work. It was a pleasure to
work with editor Tracy Cutchlow, who with patience, laughter, and
extraordinary thoughtfulness, taught me how to write.
Special thanks to Dan Storm and Eric Chudler for providing
invaluable scientific comments and expertise.
I am grateful to friends on this journey with me: Lee Huntsman,
for hours of patient listening and friendship for almost 20 years.
Dennis Weibling, for believing in me and giving me such freedom to
sow seeds. Paul Lange, whose curiosity and insights are still so vibrant
after all these years (not bad for a “plumber”!). Bruce Hosford, for
deep friendship, one of the most can-do people I have ever met.
Thanks to Paul Yager, and my friends in the department of
bioengineering at the University of Washington School of Medicine,
for giving me opportunity. I’m also grateful to my colleagues at
Seattle Pacific University: Frank Kline, Rick Eigenbrod, and Bill
Rowley, for a spirit of adventure and for tolerance. Don Nielsen,
who knew without a doubt that education really was about brain
development. Julia Calhoun, who reigns as the premier example of
emotional greatness. Alden Jones, amazing as you are, without whom
none of my professional life would work.
And my deepest thanks to my beloved wife Kari, who continually
reminds me that love is the thing that makes you smile, even when
you are tired. You, dear, are one in a million.
acknowledgements

293. INDEX
285
A
A2i (computer program), 68
Absenteeism, stress and, 185
Absent-mindedness, 143
Academic performance, factors in, 18
Action recognition, 270
Acute stress, 176
gender and, 251
Adams, Scott, 156–57
Adaptive software, developing, 69
Addison’s disease, 175
Adrenal glands, 174, 178
Adrenaline, stress and, 174, 176
Aerobic exercise, 14–15, 16
Age-related dementia, 15–16
Aging
exercise and, 12–18
factors predicting, 13
Alcoholics, gender and, 250
Alerting or Arousal Network, 79
Alertness
Intrinsic, 79
Phasic, 79
Allostasis, 182
Allostatic load, 182
Alzheimer’s disease, 16, 26–27
American fitness movement, 9
Amnesia. See also Forgetfulness
anterograde, 139–42
retrograde, 139
Amygdala, 80–81, 213
male versus female, 247
Amygdale, 40
Anecdotes, business-related, 92
Animals, comparison of brains in wild
versus domestic, 56–57
Animations, computer, 237–38
Aniston, Jennifer, neuron, 60–62
Anterograde amnesia, 139–42
Anthony, William, 167
Anxiety
exercise and, 16
stress and disorders of, 185
Aristotle, 200, 248
Armstrong, Lance, 23
Armstrong, Neil, 273
Arousal, 76
Art, capacity for, 33
Asimov, Isaac, 54
Association cortices, 204–5
Attention, 3, 71–93
awareness and, 76–78
bait the hook and, 90–92, 90–93
culture and, 76
details and, 82–84
emotions in getting, 79–82
examination of, on clinical level,
77–78
getting, 75–78
impact of sleep loss on, 163
interest and, 76
learning and, 74
memory and, 75–76
multitasking and, 84–87, 90
need for break and, 88–89
novel stimuli and, 76
pictures in grabbing, 237, 239
retention and, 74–75
10-minute rule and, 89–90
Auditory cortex, 109, 207
Auditory information, 124
Autobiographical memories, 126
retrieving, 212
Automatic processing, encoding and,
106–7
Awareness, attention and, 76–78
Axon, 54
Axon terminal, 54
B
Babies
brains in, 58–59
visual processing in, 235–36
Baddeley, Alan, 124–25
Bait the hook, attention and, 90–93
Balint’s Syndrome, 109–10

294. INDEX
286
Battle of the sexes, gender and, 248–55
Behavior
genes and, 4
influence of culture on, 256
Behavioral genetics, 248
Biases, 143
gender, 244
Binding problem, 105–6, 109–10
Bipedalism, 37, 39
Bissell, Gene, 16
Blair, Steven, 16
Blind spot, 229
Blocking habits, 143
Blood pressure, stress and, 183, 186
Bodily/kinesthetic intelligence, 64
Boeing Aircraft Company, 78
leadership-training programs of, 26
Boleyn, Anne, 245
Bologna, University of, 278
Bottom-up processing, sensory
integration and, 203–6
Brain
as amazing, 1–2
biology of, 102–3
development of connections, 59–60
differences in female and male,
247–48
evolution of human, 31–47
functional organization and
reorganization of, 57
integrative instincts of, 207–8
malleability of, 271
mapping, 64–66
memory systems in, 98
need for break, 3, 88–89
need of
for glucose, 20–21
for oxygen, 25
Paleomammalian, 40
performance envelope of, 5, 31–32
role of, in vision, 223, 224, 229–30
sensitivity to external inputs, 61
during sleep, 152–56
triune theory of, 40
wiring of, 51–70
Brain Derived Neurotrophic Factor
(BDNF), 22
stress and, 179
Brain disorders, exercise in treating,
15–17
Brain power, exercise in boosting, 3,
9–27
Brain research, advances in, 4
Brain Rules, 2–3
Brain stem, 40
Brand differentiation, use of smell in,
216–17
Branding, sensory, 215–17
Bransford, John, 84
Bringing Baby Home, 190–91
British model, sensory integration and,
202–3
Business-related anecdotes, 92
Business setting, role of learning in,
217–18
C
Cahill, Larry, 251–52, 258
Camel, visual perception of, 230–31
Carbon dioxide, 20
Cardiovascular fitness
exercise and, 13–14
stress and, 176
Career, choosing between family and,
192–93
Cause-and-effect relationships, 235
Cells
biological structures of, 53–55
nerve, 53–54
Central executive in working memory,
125
Charles Bonnet Syndrome, vision and,
229
Chestnut, Joey, 19
Children, brains in, 58–59
Chromosomes, 244–47

295. INDEX
287
sex, 244
X, 244–47, 249–50
Y, 245–46
Chronic stress, 171, 172, 176–77
Chronotypes, 156, 157
early, 157
late, 157
matching to work schedules, 165–66
Cingulate gyrus, 80
Circadian arousal system, 155, 156
Classrooms
gender arrangements in, 256–58
learning and size of, 67–68
performance in, 67
Code, cracking, 110–14
Cognition, effects of exercise on, 23
Cognitive abilities, 31–32
Cognitive blessings of exercise, 17–18
Cognitive effects of physical activity,
24–25
Cognitive neuroscientists, 4
Cognitive performance, exercise and,
14–15
Cognitive psychology, 113
Cognitive skills, influence of physical
activity on, 11–12
Coherence principle, 210
College undergraduates, quality of, 145
Color vision, 236
Combat as smelly experience, 211
Common fate, principle of, 235–36
Communication
with pictures, 239–40
verbal, 252–56
Competitive food eaters, 18–19
Computer animations, 237–38
Conflict, work-family, 188
Connor, Carol McDonald, 68, 69
Consciousness, neural location of, 77
Consolidation
fast, 135
long-term memory and, 125–27
slow, 136
synaptic, 135–36
system, 135–36, 145
Context-dependent learning, 218
Control
influence on perception of stress,
183–84
stress and, 174, 187–88
Cornea, 224
Cortex, 62
memory and, 102–3, 108–9, 112–13,
137–38
prefrontal, 39–40, 80, 132
left inferior, 132
visual, 108–9, 226
Cortisol, stress and, 174, 178, 186
Costanza, George, 16
Counseling, family, 192–93
Creativity, loss of, and health care
expenses, 187
Crime scenes, retrieval and, 128, 129,
132
Critical language area (CLA), 66
Culture
attention and, 76
influence of, on behavior, 256
Customized instruction, 68–69
Cytoplasm, 53
D
Darwin, Charles, 58
Decision making, role of smell in, 213
Declarative memories, 98, 101, 103, 141
consolidation of, 215
encoding in, 98–118
forgetfulness in, 98
life cycle of, 103
odors in retrieving, 212
retrieving, 98, 212
storage in, 98
stress and, 178
Declarative processing, forgetting in,
142–43
DeLoache, Judy, 32–33, 38, 45

296. INDEX
288
Dement, William, 151, 153–54, 156, 159
Dementia, age-related, 15–16
Dendrites, 53
Dentate gyrus, 22
Deoxyribonucleic acid (DNA), 53
Depression
exercise and, 16
stress and, 180, 185, 186–87
Details, attention and, 82–84
Dewey, John, 274–75
Diabetes, risk for, 24
Diamond, David, 173, 194
Diamond, Jared, 75
Dilbert (comic), 156–57
Discovery-based learning models, 273
Discrimination, 161
DNA, 236, 244
Dopamine, 80, 81–82
exercise and release of, 17
Dorsal stream, 228
Dreaming, 153
Drug use, gender and, 250
Dual representation, 33, 38
theory of, 32–33
E
Early chronotype, 157
Early long-term potentiation, 134–35
Ebbinghaus, Hermann, 100–101, 125,
131
Ecological niche, 35
Education
current system of, 191–92
factors in academic performance
and, 18
quality of, 45
Education college of, creation of, to
study the brain, 276–77
Effortful processing, encoding and, 107
Einstein, Albert, 193
Elaborative processing, 209
Elaborative rehearsal, 131
Electrical stimulation mapping, 64–66
Emotional environment, effect of, on
learning performance, 45
Emotional impulses, 80
Emotionally charged events, 80–81
categories of, 81
Emotionally competent stimuli (ECS),
91
Emotions
effects of, on motivations, 215–21
facts on, 256
in getting attention, 79–82
stability of, 183
Encoding, 103–4
automatic processing and, 106–7
cracking the code, 110–14
in declarative memory, 98–118
effortful processing and, 107
energy transfer in, 108–10
information, 106–10
phonemic, 108
quality of, 114–15
retrieval and, 113–14
semantic, 107–8
structural, 108
types of, 107–8
Engram, 109
Environmental cues in encoding and
retrieval, 117–18
Environmental instability, 5
Episodic buffer in working memory, 125
Episodic memory, 126
Ericsson, K. Anders, 83
Events
life-threatening, 177–78
prioritizing, 142–43
Evolutionary biologists, 4
Evolution of human brain, 31–47
Examples, providing in learning, 115
Executive functions, 40, 80
impact of sleep loss on, 163
stress and, 178
Executive Network, 79, 85–86
Exercise, 7–27

297. INDEX
289
aerobic, 14–15, 16
aging and, 12–18
anxiety and, 16
benefits of, 24
in boosting brain power, 3, 9–27
brain-specific effect of, 21–22
cardiovascular fitness and, 13–14
cognitive performance and, 14–15,
17–18
competitive food eaters and, 18–19
depression and, 16
influence on cognitive skills, 11–12,
23
integrating, into workday, 25–26
long-term memory and, 14
role of, on mood, 17
short-term memory and, 14
survival of the fittest and, 10–12
in treating brain disorders, 15–17
Exhaustive detail, power of repetition
in, 131
Experience-dependent brain wiring,
60, 61
Experience-independent brain wiring,
60, 63
Experimental psychologists, 4
Exploration, 261–80
acquisition of information in,
264–65
evolutionary needs and, 277–78
Google and, 274
as lifetime journey, 270–72
mirror neurons and, 269–70
object-orientation, 265
object permanence and, 267–68
playing pointing game, 263–64
sense of wonder and, 278–79
testing and, 268–69
tongue testing, 266–68, 269, 270
F
Faking it, 229
False information, 129–30
Familiarity
recognition memory in explaining,
232
retrieval and, 117–18
Family
choosing between career and,
192–93
counseling for, 192–93
effects of, life on business life, 188
Fantastic Voyage (Kleiner), 54
Fast consolidation, 135
Fatal Familial Insomnia, 152
Females. See Gender; Women
Fight or flight response, 174
Filling in, 229
Fischer, Edmond, 270, 272
Fluid intelligence, 17
depression and, 180
stress and, 186–87
tasks in, 14
Fogassi, Leonardo, 269
Forgetfulness. See also Amnesia
curves in, 131
in declarative memory, 98
memory and, 142–43
stress and, 180
types of, 143
Frames of Mind: The Theory of Multiple
Intelligences (Goodall), 64
Free radicals, 19–20
Frontal lobe, 39
Functional magnetic resonance
imaging, 132
G
Gage, Phineas, 39
Gamel, 171
Gaps, filling in missing, 128–30
Gardner, Howard, 63–64
Gardner, Randy, 151, 153
Gazing behavior, 235
Gender, 241–60. See also Men; Women
acute stress and, 251

298. INDEX
290
alcoholics and, 250
battle of the sexes and, 248–55
bias and, 244
cementing relationships and,
253–54
characterizing behaviors specific to,
248–55
in classroom, 256–58
dealing with traumatic situations,
250–52
defined, 244
division of differences in, 245
drug use and, 250
language and, 255
mental retardation and, 249
nature or nurture debate and,
255–56
negotiating status and, 254–55
performance gap and, 257
schizophrenia and, 250
sex versus, 244
teams in workplace, 258–59
verbal communication and, 252–53
x factor and, 244–47
General dementia, lifetime risk of, 16
General math knowledge, impact of
sleep loss on, 163
Genes, 53
behavior and, 4
purpose of, 247
SRY, 245
Glucose, 19
brain’s need for, 20–21
Gmail, 273
Goldilocks Effect, 36
Goldin, Claudia, 193
Goodall, Jane, 63
Goods, improving access to, 21
Google News, 273
Gottman, John, 189–90, 191, 192, 193
Gould, Stephen Jay, 252
Grade level expectations, learning and,
145
Grades, effects of stress on, 184–85
Griffey, Ken, Jr., 51–52
Guns, Germs, and Steel (Diamond), 75
H
Hallucinating, 228
Hamm, Paul, 23
Haseltine, Flo, 249
Hayden, Stephen, 82
Heads, size of, 37, 42–43
Healthy insomnia, 158
Hearing, multimedia and, 210
Heart disease, risk for, 24
Henry VIII, King of England, 245
Heston, Charleton, 140–41
Hippocampus, 22, 40–41, 54, 62
memory and, 103, 139–41
stress and, 177, 179
Hogan, Ben, 23
Home, stress in, 183–85
Homeostatic sleep drive, 155–56
Homework, need for, 144
Homo erectus, 11
Homo sapiens, 11
Honey, I Shrunk the Submarine, 54
Hormones, stress, 178–80
How People Learn, 84
Human genome, 246–47
Humankind, development of, 34
Human pregnancies, risks in, 43
Humans, acquisition of knowledge by,
46
Hypothalamus, stress and, 174
Hypothesis testing, exploration and,
265
I
IBM, 82
Identical twins, brain wiring in, 61–62
Images, testing power of, 239
Imitation, 269
Immediate memory, impact of sleep
loss on, 163

299. INDEX
291
Immune response, stress and, 176–78
Immune system, stress and, 186
Individuality of wiring, 62–64
Infants
acquisition of information by,
264–65
hypothesis testing by, 265
object orientation and, 265
object permanence and, 267–68
testing of new information by,
268–69
tongue testing and, 266–68, 269,
270
Information
auditory, 124
encoding, 106–10
exploration in acquisition of,
264–65
picture transfer of, 237
processing of newly acquired, 124
re-exposure to, 133
repeated exposure to, 132
sensory, 137–38
timing of, and learning, 143–46
timing of re-exposure, 143–46
Inhibition, 55
Input, spacing out, and retrieval, 131–33
Insel, Thomas, 250
Insomnia, healthy, 158
Instruction, customized, 68–69
Intellectual dexterity, 187
Intellectual progress, 34–35
Intellectual variability, 67
Intelligence, 63–64
Intelligence quotient (IQ) tests, 63
Interest, attention and, 76
International Federation of Competitive
Eating, 18
Interpersonal intelligence, 64
Intervention strategies, 190
Intrapersonal intelligence, 64
Intrinsic Alertness, 79
Introductions, 116–17
J
Jennings, Ken, 83
Jeopardy!, 83
Job performance, stress and, 188–89
Johnson, Lyndon Baines, need for nap,
158–59
Jordan, Michael, athletic failures of,
51, 52
Jumping Jack, 10
K
Kandel, Eric, 56–57, 62
Kim, Jeansok, 173, 194
Kleiner, Harry, 54
Kleitman, Nathaniel, 154–55, 156
Knowledge, acquisition of, by humans,
46
Knowledge base, retrieval and, 132
Kobayashi, Takeru “Tsunami,” 19
Krebs, Erwin, 270, 272
L
Laboratory school, creation of, at
University of Chicago, 274–75
La Lanne, Jack, 9–10, 13
Landers, Ann, 156
Language
capacity for, 33
depression and, 180
gender and, 255
mapping of brain and processing
of, 65
memory and, 99
Larks, 157
Late chronotypes, 157
Late long-term potentiation, 135
Learned helplessness, 171–72, 174
stress and, 179, 187–88
Learning, 56–57, 62
attention and, 74
in business setting, 217–18
class size and, 67–68
context-dependent, 218

300. INDEX
292
customized instruction and, 68–69
effect of emotional environment on
performance, 45
grade level expectations and, 145
importance of sleep to, 137–38
massed, 100
meaningful, 115
memory and, 98
multimedia exposure and, 208
multiple cues in, 214
multiple intelligences and, 63–64
in multisensory environment,
208–9
need for homework and, 144
review holidays and, 144
school systems and, 66–69
sleep and, 160–65
spaced, 100
stress and, 172, 178, 180–81, 184–85
timing of information and, 143–46
traumatic stress and, 46
vision and, 232–33
Learning models
discovery-based, 273
problem-based, 273
LeDoux, Joseph, 140
Left brain/right brain personalities, 4,
250
Left hemisphere, 77
Left inferior prefrontal cortex, 132
Lens, 224
Library model, retrieval and, 128
Life-threatening events, 177–78
Light, vision and, 224
Lizard brain, 40
Logical/mathematical intelligence, 64
Logical reasoning ability, impact of
sleep loss on, 163
Long-term memory, 121–47
consolidation and, 125–27
exercise and, 14
forgetting, 142–43
formation of, 137–38
repetition and, 130–38
retrieval, 127–28
Long-term potentiation (LTP), 134–35
early, 134–35
late, 135
Luther, Martin, 248
M
Macadamization, 21
Maintaining attention, 80
Malacrane, Vincenzo, 57
Males. See Gender; Men
The Man Who Mistook His Wife for a Hat
(Sacks), 77
Mapping, brain, 64–66
Marital conflict, unresolved, and stress,
183
Marital stress, effect on academic
performance, 184–85
Marriage intervention, 189–91
Mass customization, 69
Massed learning, 100
Mathematically, capacity to reason, 33
Math knowledge, impact of sleep loss
on, 163
Maugham, W. Somerset, 205
Mayer, Richard, 208, 209
rules for multimedia presentation,
210
Maze-pattern sequence, 163–65
McAdam, John Loudon, 21
McEwen, Bruce, 182
McGurk effect, sensory integration
and, 201
Medial temporal lobe, 137
Medical-school model, components of,
274–76
Medical schools, analyzing success of,
274–76
Medina Grump Factor (MCF), 5
Meltzoff, Andy, 266
Memories, 3
attention and, 75–76

301. INDEX
293
autobiographical, 126
cortex and, 102–3, 108–9, 112–13,
137–38
declarative, 98, 101, 103, 141, 178
depression and, 180
effects on vision, 232–33
episodic, 126
hippocampus and, 140–41
language and, 99
life spans of, 100
long-term, 121–47
long-term potentiation and, 133–35
loss of, 101–3
metaphor for birth of, 123
mumbo jumbo and, 98–101
nomadic, 140
nondeclarative, 101, 103
recognition, 232–33
repeating information in timed
intervals, 214
repetition in, 3, 97–119, 133
semantic, 126
separation of, from retrieval,
100–101
short-term, 95–119, 123–24
smell in evoking memory, 211–12
stability in, 127
stress and formation of, 187
types of, 101, 125
working, 87, 124–26, 143, 209
Memory trace, storage of, 111–13
Men. See also Gender
brains in, 247–48
memory and, 251
Mendeleyev, Dimitri Ivanovich, 160–61
Mental retardation, gender and, 249
Mesulam, Marcel, 77
MetroNaps, 166
Micro-hibernation, 153
Micron, 53
Milner, Brenda, 102
Mirror neurons, exploration and,
269–70
Misattribution, 143
Mistakes, learning from, 5
Modality principle, 210
Mondo Cane, 88
Mood
impact of sleep loss on, 163
retrieval and, 113–14
role of exercise on, 17
Morrow, Barry, 98
Motivations, effect of emotions on,
215–21
Motor adaptations, 161
Motor sequencing, 161
Mozart Effect, 4
Multimedia exposure, link between
learning and, 208
Multimedia principle, 210
Multimodal reinforcement, sensory
integration and, 207
Multiple Intelligences movement,
63–64
Multiple reinstatements, 144
Multisensory environment, learning in,
208–9
Multisensory inputs, benefits of, 208
Multisensory school lessons, 214–15
Multitasking, attention and, 84–87, 90
Mumbo jumbo, memory and, 98–101
Musical/rhythmic intelligence, 64
Myers-Briggs personality tests, 68
N
Najdorf, Miguel, 124
Naps
benefits of taking, 3
need for, 158–60
promoting, 166–67
Nap zone, 156, 159–60
National Napping Day, 167
Nature or nurture debate, gender and,
255–56
Negotiating status, gender and, 254–55
Nerve cells, 53–54

302. INDEX
294
Neural location of consciousness, 77
Neural road map, 269
Neurons, 42, 54, 55
learning and, 57
mirror, 269–70
postsynaptic, 55, 134
presynaptic, 55, 134
retinal, 228
visual receptor, 213
Neurotransmitters, 55–56
Neurotrophins, stress and, 179
Nitric oxide, 21
Nobel, Alfred, 57
Nomadic memory, 140
Nondeclarative memories, 101, 103
Non-REM sleep, 153
Norepinephrine, exercise and release
of, 17
Novel stimuli, attention and, 76
Nowak, Lisa, 185–86
Nuclear annihilation, 136
Nucleus, 53
O
Object-orientation, 265
Object permanence, 267–68
Occipital lobe, 226
Odors in retrieving declarative memory,
212
Of Human Bondage (movie), 205–6
Ojemann, George, 64–66
Olfactory epithelium, 213
Olfactory region, 212–13
Opponent process model, 154
Optic disk, 228–29
Optic nerve, 224, 226
Oral presentations, 233–34
Orienting Network, 79
Orwell, George, 82
Owls, 157
Oxygen
brain’s need for, 25
function of, 20
P
Page, David C., 245
Paleomammalian brain, 40
Pattern matching, 82
Payne, William H., 275
Peek, Kim, 97–98, 106
Perception, 200–201
Performance envelope, 31–32
Performance gap, gender and, 257
Phantom-limb experiences, 232
Phasic Alertness, 79
Phonemic encoding, 108
Phonological loop in working memory,
124–25
Phospholipid bilayer, 54
Photon, 225
Physical activity
cognitive effects of, 24–25
influence on cognitive skills, 11–12
Physical education, elimination from
curriculum, 24–25
Physical health, stress and, 185
Pictorial superiority effect (PSE), vision
and, 233–35
Pictures
communication with, 239–40
in grabbing attention, 237, 239
retrieval of recognition information,
233
Pointing game, playing, 263–64
Posner, Michael, 78–79, 85–86
Post-synaptic neurons, 55, 134
Post-traumatic stress disorder (PTSD),
211
Potts, Richard, 37
PowerPoint, vision and, 239
Prefrontal cortex, 39–40, 80, 132
left inferior, 132
Presynaptic neuron, 55, 134
Problem-based learning models, 273
Problem-solving abilities, 80
stress and, 187
Productivity

303. INDEX
295
control and, 188
effect of turnover on, 187
Propranolol, 251
Proust, Marcel, 211
Proust effect, 213
sensory integration and, 211, 212
Puberty, brains at, 59
Q
Quality
of education, 45
of encoding, 114–15
Quantitative reasoning
depression and, 180
impact of sleep loss on, 163
stress and, 187
Quiroga, Quian, 61
R
Rain Man, 106
Rain Man (film), 98
Ramachandran, Vilayanur, 229
Random genetic mutations, 38–39
Rapid eye movement (REM) sleep,
154–55, 165
Real world
consistent exposure to, 274–75
traditional book learning and needs,
276
Recess, elimination of, from school day,
24–25
Recognition memory, 232–33
in explaining familiarity, 232
Reconsolidation, 127
Rehearsal, elaborative, 131
Relationships, gender in cementing,
253–54
Remembrance of Things Past (Proust),
211
Repetition, memory and, 3, 97–119,
123–47
Research programs, consistent exposure
to practical, 276
Retention, attention and, 74–75
Retina, 224, 225
Retinal neurons, 228
Retrieval
crime scenes and, 128, 129, 132
in declarative memory, 98
encoding and, 113–14
familiar settings and, 117–18
filling in missing gaps in, 128–30
library model and, 128
in long-term memory, 127–28
memory and, 99
separation of memory from, 100–
101
Sherlock Holmes model, 128
spacing out input in, 131–33
Retrograde amnesia, 139
Re-uptake, 56
Review holidays, 144
Right brain, left brain versus, 250
Right hemisphere, 77
Rosekind, Mark, 167
Routing, 202–3
S
Sacks, Oliver, 77, 104, 204
Schacter, Dan, 133, 143
Schizophrenia, gender and, 250
School performance, stress and, 188–89
School systems, learning and, 66–69
Scoville, William, 102
Second brain, 40
Seligman, Martin, 171–72, 187, 194
Semantic encoding, 107–8
Semantic memory, 126
Sensation, 202
Sense of wonder, exploration and,
278–79
Sensory branding, 215–17
Sensory information, 137–38
Sensory integration, 197–219
American model in, 203
association cortices and, 204–5

304. INDEX
296
bottom-up processing, 203–6
brain’s integrative instincts and,
207–8
branding, 215–17
British model of, 202–3
declarative-memory consolidation
and, 215
Mayer, Richard, and, 209–10
McGurk effect and, 201
multimodal reinforcement and, 207
perception in, 200–201, 203
Proust effect and, 211, 212
routing in, 202–3
sensation in, 202
Shereshevskii, Solomon, and,
209–10
synesthesia and, 199–200, 206
theories of, 201–3
top-down processing and, 203–6
working memory in, 209
Sequential actions, 86–87
Serotonin
exercise and release of, 17
in regulating emotion and mood,
247–48
Services, improving access to, 21
The Seven Sins of Memory (Schacter),
143
Sex, 244. See also Gender
Sex chromosomes, 244
Sex-inhibiting threats, 175
Shapiro, Alyson, 190, 191
Shaw, George Bernard, 235
Shereshevskii, Solomon, 142–43,
209–10
Sherlock Holmes model of retrieval,
128
Short-term memory, 95–119, 123–24
conversion of, to longer-term
memory, 125–27
exercise and, 14
Simultanagnosia, 109
Sleep, 149–68
amount needed, 158
brain during, 152–56
importance of, 138, 167
learning and, 138, 160–65
non-REM, 153
rapid eye movement (REM), 154–
55, 165
slow-wave, 164–65
Sleep deprivation, 159
effects of, 151–52, 163, 165
Sleep Pod, 166
Slow consolidation, 136
Slow-wave sleep, 164–65
Smell, 236
in brand differentiation, 216–17
in decision making, 213
in evoking memory, 211–12
learning and, 214
Software
A2i, 68
developing adaptive, 69
Spaced learning, 100
Spangenberg, Eric, 216
Spatial contiguity principle, 210
Spatial intelligence, 64
Spatial perception, depression and, 180
SRY gene, 245
Stability in memory, 127
Status, gender in negotiating, 254–55
Storage
in declarative memory, 98
memory and, 99
Stress, 169–95
absenteeism and, 185
acute, 176, 251
allostasis and, 182
anxiety disorders and, 185
biology of, 194
blood pressure and, 183, 186
Brain Derived Neurotrophic Factor
(BDNF) and, 179
cardiovascular performance and,
175, 176

305. INDEX
297
chronic, 171, 172, 176–77
control and, 187–88
cortisol and, 174, 178, 186
declarative memory and, 178
defined, 172–74, 194
depression and, 185, 186–87
effect on learning, 178
emotional stability and, 182–83
executive function and, 178
fight or flight response and, 174
fluid intelligence and, 186–87
Gamel and, 172
hippocampus and, 177
in home, 183–85
immune response and, 175–78, 180
job performance and, 188–89
learned helplessness and, 171–72,
174, 179, 187–88
learning and, 172, 180–81, 184–85
marriage intervention and, 189–91
memory formation and, 187
neurotrophins and, 179
physical health and, 185
physical responses to, 174–75,
181–82
problem-solving abilities and, 187
quantitative reasoning and, 187
school performance and, 188–89
sex-inhibiting threads and, 175
successful management of, 194
toxic effects of, 24
truancy and, 185
types of, 171–72
unevenness of human response to,
181
at work, 185–89, 194
Stress hormones, 178–80
Stroke, risk for, 24
Structural encoding, 108
Suggestibility, 143
Summers, Larry, 248, 256, 259
Supra-additive integration, 208
Suprachiasmatic nucleus, 155
Surgery as smelly experience, 211
Survival, 29–47
adapting to variation, 37
anatomy of brain and, 39–43
bipedalism and, 37, 38–39
increased head size and, 37, 42–43
new rules for, 35–37
odds against, 37–38
prediction of mental state, 44
random genetic mutations and,
38–39
symbolic reasoning and, 32, 33–34
teamwork and, 43–44
Theory of Mind, 44
Variability Selection Theory and,
37–38
Survival of the fittest, 10–12
Symbolic reasoning, 34
ability to use, 32
survival and, 32, 33–34
Synaptic cleft, 55
Synaptic consolidation, 135–36
Synesthesia, 206, 209
sensory integration and, 199–200
System consolidation, 137, 145
timing properties of, 136–38
T
Tabula rasa, 264
Tannen, Deborah, 252–56
Task-switching, 87
Teachers
pictures in grabbing attention, 237
use of computer animations, 237–38
Teamwork
survival and, 43–44
in workplace, 258–59
Television advertising, emotionally
charged events and, 80, 82
Temporal contiguity principle, 210
Temporal lobe, 102
memory and, 103
10-Minute rule, attention and, 89–90

306. INDEX
298
Tend and befriend tendency in females,
251–52
Testing, exploration and, 268–69
Text
inefficiency of, 234
presentation pf, 233–34
Thalamus, 213, 226
Theory of Mind skills, 44, 67, 69
Timing principle, 116–17
Tip-of-the-tongue issues, 143
Toddler’s Creed, 268
Tongue testing, 266–68, 269, 270
Top-down processing
interpretative activity as, 205
sensory integration and, 203–6
Touch, learning and, 214
Tracks, 225–26
Traumatic situations, dealing with,
250–52
Traumatic stress, learning and, 46
Trinity Model, 78–79
Triune theory of brain, 40
Truancy, stress and, 185
Turnover, effect on productivity, 187
U
Unisensory environment, learning in,
208
Universally experienced stimuli, 81
USA Today, 238
V
Variability Selection Theory, 37–38
Variation, adapting to, 37
Ventral stream, 228
Verbal communication, gender and,
252–53
Verbal/linguistic intelligence, 64
Viorst, Judith, 215
Vision, 221–40
in babies, 235–36
Charles Bonnet Syndrome and, 229
communication with images, 239–40
computer animation and, 237–38
internal mechanics of, 224
learning and, 232–33
light and, 224
memory and, 232–33
multimedia and, 210
perceived reality and, 228
phantom-limb experiences, 232
pictorial superiority effect and,
233–35
pictures in grabbing attention, 237,
239
PowerPoint presentations and, 239
role of brain in, 223, 224
testing power of images, 239
Visual-capture effect, 232
Visual cortex, 108–9, 226
Visual information in working memory,
125
Visual processing, modularity of visual,
227
Visual receptor neurons, 213
Visual short-term memory, 233
Visual system as bottom-up processor,
205
Visual texture, 161
Visuo-spatial sketchpad in working
memory, 125
W
Wagner, Robert, 133, 144
Wallace, Mike, 12
Whitehead, Barbara, 185
Wine tasting, vocabulary of, 223–24
Wiring, 49–70
of brain, 51–70
cells in and, 52–55
experience-dependent, 60, 61
experience-independent, 60, 63
individuality of, 62–64
learning and, 56–58
mapping of brain and, 64–66
Women. See also Gender

307. INDEX
299
brains in, 247–48
memory and, 251
tend and befriend tendency in,
251–52
Work, stress at, 185–89, 194
Workday, integrating exercise into,
25–26
Work-family conflict, 188
Working memories, 87, 124–26, 143,
209, 233
central executive in, 125
episodic buffer in, 125
impact of sleep loss on, 163
phonological loop in, 124–25
visual information in, 125
visuo-spatial sketchpad in, 125
Workplace
gender teams in, 258–59
naps in, 167
Work schedules, chronotypes matching
to, 165–66
Wrangham, Richard, 10–11
Wright, Frank Lloyd, 12–13
X
X chromosomes, 244–47, 245–46,
249–50
X factor, gender and, 244–47
X inactivation, 246
Y
Yancey, Antronette, 18, 24–25
Y chromosomes, 245–46

309. 301
dr. john j. medina is a developmental molecular biologist focused
on the genes involved in human brain development and the genetics
of psychiatric disorders. He has spent most of his professional life as
a private research consultant, working primarily in the biotechnology
and pharmaceutical industries on research related to mental health.
Medina holds joint affiliate faculty appointments at Seattle Pacific
University, where he is the director of the Brain Center for Applied
Learning Research, and at the University of Washington School of
Medicine, in its Department of Bioengineering.
Medina was the founding director of the Talaris Research
Institute, a Seattle-based research center originally focused on how
infants encode and process information at the cognitive, cellular, and
molecular levels.
In 2004, Medina was appointed to the rank of affiliate scholar
at the National Academy of Engineering. He has been named
Outstanding Faculty of the Year at the College of Engineering
at the University of Washington; the Merrill Dow/Continuing
Medical Education National Teacher of the Year; and, twice, the
Bioengineering Student Association Teacher of the Year. Medina
has been a consultant to the Education Commission of the States
and a regular speaker on the relationship between neurology and
education.
Medina’s books include: The Genetic Inferno; The Clock of
Ages; Depression: How it Happens, How it Heals; What You Need to
Know About Alzheimer’s; The Outer Limits of Life; Uncovering the
Mystery of AIDS; and Of Serotonin, Dopamine and Antipsychotic
Medications.
Medina has a lifelong fascination in how the mind reacts to and
organizes information. As a husband and as a father of two boys,
he has an interest in how the brain sciences might influence the
way we teach our children. In addition to his research, consulting,
and teaching, Medina speaks often to public officials, business and
medical professionals, school boards, and nonprofit leaders.
www.johnmedina.com
about the author

311. www.brainrules.net